How to Make a Cardigan Onesie: UPDATED

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Learn how to make a baby cardigan onesie with a simple DIY tutorial. This baby sewing project is fun and easy to make!

Little babies are so fun to sew for. They look so cute in anything you make with their soft skin and sweet smiles. My favorite way to sew for babies is to refashion or upcycle something. That way I can fit in a small project between all their baby needs.

I’m excited that I’ve redone my original and popular cardigan onesie tutorial. The pictures needed updating since the original is 4 years old, and those little babies have grown up. Now I have a cute little baby girl to photograph wearing a cardigan onesie!

Cardigan Onesie Tutorial: UPDATED //

I made this version way simpler so it’s easier and quicker to make. (You can also try the simplest and easiest cardigan onesie.) This is a girly version, but I love that cardigan onesies work well for both boys and girls. I can’t wait to pair this cardigan onesie with a little skirt and knee high socks.

I also added a cardigan onesie tutorial video to the end!

How to Make a Cardigan Onesie



Sew the overlapping shoulders together so that they aren’t separate. I sewed mine with a straight stitch since this part doesn’t need to stretch. I sewed my straight stitch one top of the original stitching so you wouldn’t see it.

Cut the edge of the neckline off and cut a v-neck. Cut straight down the center front with a little detour between two of the snaps at the bottom. 

Measure the total length of the edges you just cut.

If you are using a ribbing with 50% stretch and good recovery multiply the length by 80%. If using ribbing with more than 50% stretch and less recovery multiply the length by 75% or less.

Cut this long length with the long side going with the stretch of the ribbing. The height of the ribbing should be between 2″.

Fold the ribbing right sides together and lengthwise. Sew the short edges together at 1/4″. Trim the corner. Turn right side out. Do the same to the other short end.

Fold the ribbing in half lengthwise. Pin the center of the ribbing to the center back of the neckline.

Pin the finished ends of the ribbing to the bottom edge of the onesie near the snaps. Dividing each piece in sections, stretch and pin all along the edge.

Sew the ribbing to the onesie with a zigzag stitch. Carefully stretch the ribbing to fit the onesie but don’t stretch the onesie while sewing.

Finish the edges with a serger or zigzag stitch. Press well.

Sew the seam allowance towards the body of the onesie with a straight topstitch.

Add snaps or buttons depending on the look you’re going for to close the front like a cardigan. You’re done!

Cardigan Onesie Tutorial: UPDATED //
diy cardigan onesie tutorial

Baby Cardigan Onesie Tutorial

Yield: 1 baby cardigan onesie
Prep Time: 15 minutes
Active Time: 30 minutes
Total Time: 45 minutes
Difficulty: Confident Beginner
Estimated Cost: $15

Learn how to make a baby cardigan onesie with a simple DIY tutorial. This baby sewing project is fun and easy to make!


  • Long or short sleeved onesie- (I think the short sleeved ones look best on girls.)
  • RIBBING (make your life easier by using ribbing with spandex!)
  • Buttons or snaps


  • Sewing tools
  • Sewing machine


  1. If your onesie has crossover shoulders, find where the crossover lays flat and pin two layers together.
  2. Sew with a straight stitch the two layers together so they don't come apart.
  3. Measure across the front of the onesie and mark the center all the way down. At the bottom slant to one side between two of the snaps.
  4. Cut on the line.
  5. Draw from shoulders to parallel with the armpits.
  6. Cut on lines up around the neckline so that you cut off the neck band.
  7. Measure the whole length of the cut edge. Take the measurement and multiply by .8. Add 1/4" seam allowance.
  8. This is the length of the front band. I wanted my band to be 3/4" tall, so double that amount and add 1/4" seam allowance. Make sure the stretch goes with the long sides.
  9. Sew ends at 1/4".
  10. Turn right side out and poke out corners.
  11. Find the center of the band and then the center of each side, so you divide the band into four sections.
  12. Use the same method to divide the cut edge of the onesie into four sections. Match pins.
  13. Stretch each section and pin so the excess is distributed evenly.
  14. Stretch while zigzagging at 1/4".
  15. Zigzag the edges of the snap facing to prevent fraying.
  16. With your machine set on to a straight stitch, stretch and sew the seam allowance towards the onesie. Sew at 1/8". Careful when going over the shoulders.
  17. Snap the snaps together overlapping the two sides.
  18. Pin the two layers together and sew together.
  19. Pin two layers of the front band together at three or four places. Sew buttons on at each pin.

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Enjoy the cute, preppy baby cardigan onesie tutorial! If you make something using this tutorial, I’d love to see! Please share it on social media with the hashtag #heatherhandmade and tag me!

Cardigan Onesie Tutorial: UPDATED //

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Maggie's tongue!! I also love the little pink detail!