A Helpful Illustrated Guide On How to Sew a Baby Onesie

Updated: Jul 9

Sewing Patterns, Sewing tutorials, How to sew, Sewing projects, sewing pattern for kids
A Helpful Illustrated Guide On How to Sew a Baby Onesie

Welcome to our helpful illustrated guide on how to sew this baby onesie.

I highly recommend that you read through this guide before you start sewing. You can find the Onesie pattern will at the bottom of this page.


The Tools:

Sewing tools, onesidress for babies
The tools I use: Don't worry. You don't need this many tools.

What you need to make this Baby onesie is not as much as this. However, you need something to cut with, some clips or pins, and a sewing machine. I have a lot of other tools as well. It makes the job a lot easier. If you are new to sewing and you want my helpful beginner's tool guide, click here.

1. Preparing the Pattern and cutting the fabric

cutting baby onesiedress free pattern
Here I am cutting the front piece of the onesiedress.

Preparing the patterns and cut the fabric.

We start by cutting the fabric according to the patterns.

Our patterns are very straightforward; We print the pattern size we want in an A4 format. We then lay the patterns on top of the fabric, and we cut around it. I cut out one front piece, one back piece, and two sleeves. When I cut the sleeves, I fold the fabric to get both pieces at once.


2. The shoulder seams

sewing onesiedress for babies
Sew the shoulder seams

When all the pattern pieces are ready, I attach the front and back pieces at the shoulder seam with glue and clips. This seam has to be inside the garment, so the pattern pieces are lying in opposite directions. Technically inside out. When I've prepared these pieces, I sew the shoulder seams. If you need to see a instructional video on the shoulderseam, I will leave a link to it at the bottom of this page.

3. The sleeves

Sewing Patterns, Sewing tutorials, How to sew, Sewing projects, sewing pattern for kids
Sewing Patterns, Sewing tutorials, How to sew, Sewing projects, sewing pattern for kids

I attach both arms with clips. The rounded side should be against the back and front piece. I fold the fabric and cut a very small notch. Then I know where the sleeves Center point is. I place the center point on the shoulder seam we just made. I use glue and clips when I prepare the sleeves to the garment. When both have been placed correctly on the garment, I sew it.

sewing a onesie
With the sleeves, its really starting to look like a onesie


4. The Rib and the Sleeves wrist

Baby Onesie rib
I Fold the rib like this
Baby onesie sleeve folds
Folding the sleeve ends

I fold the rib vertically and make a seam where the ends meet. I then sew them the ends together with a sewing machine.

I then place the rib in the neck opening. For a nice extra result, Align the rib seam we just made with one of the shoulder seams. I Use glue and clips to get a perfect result in the neck opening. We then create a simple Fold on both wrists. The fold is 2,5 centimeters on both sides. Make sure to use an overlock machine or choose extra nice stitches on your sewing machine for the wrists because this seam will be visible. I stretch the rib gently while I'm sewing it in the neck opening. Be careful, so you don't stretch the other fabric.

5. The first Sideseam

Onesiedress Sideseam
Start and stop, use glue or be extra carefull at the contact points. Remember to turn the onesie inside out.

The sideseam starts at the end of the sleeve and goes all the way to where the diaper holder starts. See the red line in the picture. The contact points are essential. There are three contact points on each side seam. They are where the sleeve starts, where the sleeve hits the main fabric, and at the bottom, where the diaper holder starts. Be extra cautious here, and I use glue to make sure that they are correctly aligned. Use the red line in the image above to reference where to start and where to stop sewing. Remember to turn the garment inside out because we want this seam to be inside the onesie. I do one sideseam. We do the other sideseam when we have sewn the diaper holder's edge ribbon.

6. The Edge Ribbon

Onesie edging
Without the Edge Ribbon
Edge ribbon
With the Edge Ribbon

The edge ribbon at the bottom of the diaper holder gives the onesie a nice, professional look. The edge ribbon also protects the fabric from ripping and provides extra strength to the buttons that we will add later.

I use a folder device on my overlock machine. If you dont have an overlocker, fasten it with pins and use twin stitching on a regular sewing machine.