How to Sew Knitted Pieces Together

How to Sew Knitted Pieces Together

Learning how to sew knitted pieces together is a simple task, compared to the knitting process you just finished. All you need is this detailed guide and suitable materials to help you crack the skill in a flash.

You can use different methods and stitches when learning how to sew knitting together, although it depends on your prowess, type of knitted fabric, and the initial knitting design. This video tutorial explains how to join knitted pieces together. Below are different methods you can use when joining knitted pieces.

How to Sew Knitted Pieces Together using Different Stitches

You can use several options to finish your work, even if you’re a beginner learning how to knit two edges together. To join knitting fabric with an invisible seam, you’ll use a mattress stitch, backstitch or whip stitching if you want a visible seam and vertical invisible seaming if you want a little edge texture.

Materials Required

    • Darning needle
    • Yarn (matching color with the knit fabric)
    • Scissors
    1. Mattress Stitch

This stitch is easy to understand and sew, as shown on this video thus recommended as the best way to sew up baby knitting.

Let’s get started.

Step 1: Place the pieces you want to join on a flat surface and bring their edges closely together as if you want to know how to read knitting patterns

Step 2: Measure the size of your knit fabric that you want to join using the thread you remained when knitting and cut three times the length. Thread your darning needle with at least 10 centimeters of the yarn and tie a knot at the bottom to keep it secure.

Step 3: Start sewing from the bottom corner of the right piece by inserting the needle from the back to the front of the first stitch. Pull the yarn loosely as you‘ll tighten it later.

Step 4: Find the gap with horizontal bars by pulling the next stitch apart. Insert the needle below two horizontal bars and pull the yarn up while avoiding bringing the pieces too close together.

Step 5: Insert the needle into the opposite knit piece and pull it apart to reveal the horizontal stitches within the bars.

Since you started with inserting the needle under two horizontal bars, continue with the same pattern. However, you can uniformly change to one horizontal bar if you want a tighter seam.

Step 6: Alternate your mattress stitch between the left and right knitted pieces until you reach about two centimeters.

Step 7: Place the joined pieces on a flat surface and press down using one hand while you pull the yarn using the other hand to tighten the stitch gently—you will see the joint disappear.

Step 8: Repeat steps six and seven until you finishing sewing your knitted pieces together. Ensure you don’t pull the yarn tightly as the pieces will bunch together.

Step 9: Tie off and cut the yarn at the end of the seam after you have entirely joined the two pieces together. Ensure you leave two inches of yarn that you’ll use when learning how to weave in ends.

That’s how to knit two pieces together using a mattress stitch that is best for joining sleeves.

      2. Back Stitch or Whip Stitching

How to sew knitted pieces together
Image Source: Wiki How

Step 1: Hold the two knit pieces together and hold the right sides of the knit pieces. Ensure that the wrong sides face each other and the edges are not flat on your working surface.

Step 2: Pull yarn equal to three times the length of your knitted fabric and thread your darning needle, which you will insert between the knit pieces.

Tie a knot at the end of your yarn to secure the end when sewing, then horizontally insert your needle through the pieces. Pull the thread to ensure the stitches are even.

Step 3:  Move around the edge and appear in the same spot. Insert the needle into the next stitch on the left knitted pieces if you had started with the right side, then pull it through the other piece.

Step 4: Continue backstitching by returning the needle to the right and left piece then pulling the yarn until both the pieces join.

Step 5: Pull the yarn gently but tightly to create a soft finished seam, then knot the yarn through the last stitch. Cut the yarn at two centimeters to help in weaving in the end.

The stitch is appropriate for joining square pieces that make a blanket

      3. Vertical Invisible Top Stitch

Invisible seam garter
Image Source: Knit with Henni

Step 1: Place your knitted pieces on a flat surface and bring them close together with the right side facing up.

Step 2: Thread your tapestry needle with a yarn three times the size of your knitted fabric. Remember to secure your yarn by making a knot at the end.

Step 3: Insert the sewing needle under the first stitch on the horizontal bar of either the right or left piece.

Step 4: Pull the yarn and insert it through the other knitted piece using the needle gently. Turn the needle on the other side and insert it on the stitch above the current stitch and yarn.

This method involves alternating the needle from the bottom to the top of the knitted pieces.

Step 5: Repeat step four until the end of the knitted pieces as you maintain an even space between your stitches. Don’t pull the yarn too tightly, as the pieces will bulge while you risk breaking your knitting yarn.

Step 6: Gently pull the yarn to ensure the seam is secure and the sewing stitches are invisible. Pull the yarn through the last stitch, make a knot, and cut the yarn leaving two inches for weaving in the ends. This stitch is suitable for light knits.

Stitch Name 

Best for


Light knits

Whip Stitch

Joining Squares

Mattress Stitch 


Zigzag Stitch

Joining Seams using machine

How to Join Shoulder Seams in Knitting a Sweater

How to sew knitting together
Image Source: Ysolda

Many knitted sweaters have shoulder seams. And you require a guide on how to seam knitting and a perfect stitch to pull the pieces together. Fortunately, there are many options on how to join shoulder seams in knitting.

 You can also watch this video to get more insights on how to join shoulder seams.

However, the most common joining methods are three-needle bind-off and the mattress stitch. You can also use this method when learning how to attach knitted pieces together. Below is their guide.

    1. Three- Needle Bind –Off

How to seam knitting
Image Source: Interweave

When you knit a sweater, and the shoulders are not ‘‘stepped”, you’ll end up with a single row of stitches. Therefore, you’ll use a three-needle bind-off, which will make a visible seam on the RS of the sweater.

      2. The Slip-Stitch Bind Off

How to join knitted pieces
Image Source: 10 Rows a Day

This is the best stitch for joining knit pieces. It’s sturdy and looks good on both ends as it doesn’t show. This stitch works for any type of sweater and provides stability as the three-needle bind–off, making a nice curve along the shoulders.

Ensure you don’t pull the yarn too tight, to prevent the fabric from bulging.

How to Assemble Knitted Sweater

How to assemble a knitted sweater
Image Source: Pinterest

Assembling a knitted sweater is simple, although some knitters view it as the most tedious part of the knitting process because it lasts after a long day of work.

You’ll need to bring all the sweater pieces that you have knit, place them on the table to form a sample image of what you’ll be expecting to achieve. Here are the steps that you’ll follow.

Step 1: Get a tapestry needle, leftover yarn, and maybe a cup of coffee to psyche you up. Start by confirming that you have weaved in the ends of all the knit pieces. This will make your work easier when assembling the pieces, as the ends usually slow you down.

Step 2: Use a steam iron to flatten the knit pieces to align the edges easily.

Note: You are not ironing the sweater! You are using the moisture part of your iron to over press the edges.

Step 3: Ensure all the pieces are correctly set. Thread your tapestry needle with a yarn three times your edge length, then use mattress stitch to assemble the pieces. This stitch creates an invisible seam when joining two edges.

Step 4: Use stitch markers to help you align the RS of the two pieces you are starting to join.

Step 5: Start by joining one sleeve to the back and work using mattress stitch while the RS is facing you. Next, join the other sleeves to the back and finish by joining the front to each sleeve.

Step 6: Finish by inserting custom woven labels and stitching the sides starting at the bottom and moving upward towards the armpits using the same mattress stitch. Ensure the pieces are neatly joined together without bulking up.

Step 7: Do you remember how to pick up stitches in knitting? That’s the skill you‘ll use to knit your neckline. Therefore to avoid disappointment when you finish your project, twist every stitch as you knit along the first row. 

When knitting the neckline, you can create gaps if you’re not careful. Therefore, twist every stitch as you knit along the first row to avoid disappointment when you finish your project.

How to Sew a Flat Seam in Knitting

How to sew a flat seam in knitting
Image Source: Dummies

When thinking about how to start knitting a blanket, it’s advisable to think about how to sew knitted seams. This is because your seaming method is determined by how you worked the knitted fabric.

For example, in flat seaming, you don’t need to slip the edge stitches. Instead, you’re supposed to knit all of them, even when learning how to change colors in knitting.  Below is how to sew a flat seam in knitting;

    • With the RS facing each other, place the knitted pieces on top of each other.
    • Thread the tapestry needle with one of the tails you left when casting on or casting off and from any piece. You may also use a new yarn if you left a small tail –the yarn should be at least three inches.
    • Insert the needle from front to back through the purl stitch, then pull the yarn away from you.
    • Insert the needle again but from back to front through the next two P stitches and gently pull the yarn to avoid puckering the seam you’ve made.
    • Repeat the process until the whole seam is joined. You can also check more sewing room ideas for a seamless finish
    • Leave a three-inch tail, then cut off the rest of the yarn, which will help you weave in the ends as you finish.




Right Side


Left Side



How to Sew a Knitted Jumper Together Using a Machine

Many knitters enjoy finishing the project when learning how to knit a sweater or jumper but dread how to seam a knitted sweater by hand.

 Although sewing jumper pieces by hand is not an easy task, it’s a straightforward process. Fortunately, with the advanced technology, you may use a serger or a sewing machine to do the work for you.

All you need is the right needle, stitch, thread, and the correct tension to seam the pieces together and efficiently.

Materials Needed

    • Water laundry detergent
    • Stretch needle (75/11,90/12)
    • Knit Jumper pieces
    • Serger
    • Sewing thread (poly/cotton)
    • Pins
    • Towel

Step 1: Start by washing your knitted jumper pieces in the laundry detergent and using your hands. Lightly press the jumper to release excess water. Ensure there is no dripping water.

Step 2: Spread the jumper on a flat surface and on top of the towel to dry.

Step 3: Turn the jumper inside and place the open ends RS together, then use stitch markers or fabric pins to keep the seam together.

Step 4: Use a matching cotton/poly yarn color to thread your machine. Use your preferred needle size to match your jumper texture.

Step 5: Use a zigzag stitch to sew the seams using 2.0 millimeters for the width and length. This thickness will help seams to stretch with the knit. If you’re using a serger, use a three-thread overlock stitch and ensure you set a balanced tension.

Step 6: Finally, finish the edges of the seam with a zigzag stitch of 2.0 mm long and 3.5 mm wide. Ensure you run the stitches over the edges of your knit jumper to the RS seam stitch.

This finishing prevents the edges from unravelling. When using a serger, stitch three threads to finish the ends. Your jumper is now ready. Flip it inside out!

How to Stitch Knitted Pieces Together by Hand

How to knit two pieces together
Image Source: Ohlalana

By now, you know how to knit a blanket using different patterns and styles. This guide will help you understand how to stitch knitted pieces together by hand and using mattress stitch. You can also use it when practicing how to knit pieces together using knitting needles.

Step 1: Prepare and stretch all the pieces that you want to join to make a blanket. Place them on a flat surface to demonstrate how you want them to look after stitching them up.

Step 2: Thread your darning needle with the leftover yarn. Since this is a big project, cut a yarn size three times the length of your to be blanket.

Step 3: Ensure all the pieces are facing RS up and insert your needle on the first stitch of the first piece.

Note: You can only stitch two pieces at a time!

Step 4: Push the needle across and through the LS corresponding stitch, then gently but tightly pull the yarn away from you.

Step 5: Continue alternating stitching until you finish the two pieces. Instead of cutting the yarn, place the following pieces and continue stitching upward.

Step 6: Repeat step five until all the pieces are stitched as one large piece. Don’t forget to insert and stitch custom care labels.

 Make a knot on the tail end, then cut off the excess yarn leaving enough to weave in ends.


Learning how to sew knitted pieces together is simple. Once you learn how to knit, other vocabularies that come with knitting will be easy to understand.

While beginners view it as a daunting task, intermediate and experienced levels find it easy although boring since it comes after knitting your project.

Which project are you sewing together?