Looking for a bold and elegant piece to add to your wardrobe? This DIY one-shoulder dress with a side slit is the perfect choice. It’s simple to sew, modern, and perfect for parties, date nights, or even casual outings depending on your fabric choice. In this tutorial, you’ll find the free sewing pattern and a complete step-by-step guide to make this stunning dress.
✂️ Materials You’ll Need
- 1.5 m of stretch fabric (knit, lycra, ribbed cotton, or viscose)
- Matching thread
- Fabric scissors
- Sewing machine or serger
- Measuring tape
- Pins or sewing clips
📏 Free Sewing Pattern
This pattern is designed for Size L and already includes 2 cm seam allowance. Adjust measurements slightly if you need a smaller or larger size.
Pattern Breakdown:
- Front piece – 80.5 cm long x 35 cm wide at the bust, with an asymmetrical neckline.
- Strap (Tirante) – 25 cm x 4 cm (cut once).
- Side shaping – curved seams ensure a fitted waist and hip.
- Slit opening – optional, but included in the design for a bold effect.
🧵 Step-by-Step Sewing Instructions

1. Cutting the Fabric
- Cut 1 front piece on the fold.
- Cut 1 back piece (mirror the front, without the neckline curve).
- Cut 1 strap piece (25 cm x 4 cm).
2. Sewing the Dress Body
- Sew the side seams (front to back), right sides together.
- Sew the shoulder seam for the one-shoulder design.
3. Adding the Strap
- Fold the strap piece lengthwise, sew along the edge, and turn inside out.
- Attach it securely to the one-shoulder neckline for extra support.
4. Shaping the Slit
- Mark the slit height on the side seam (about 23 cm from the hemline).
- Sew the seam below the slit opening.
- Fold and hem the slit edges neatly.
5. Finishing the Edges
- Fold the neckline edges inward and sew with a stretch stitch.
- Hem the bottom of the dress with a twin needle or zig-zag stitch.
💡 Extra Sewing Tips
- Use a medium-weight stretch fabric for a snug and elegant fit.
- Adjust the slit height depending on how bold you want the look.
- Add lining if your fabric is too thin.
✅ Final Thoughts
This DIY one-shoulder asymmetrical dress pattern is stylish, sexy, and surprisingly easy to make. With just a few seams and an asymmetrical neckline, you’ll have a unique dress ready for special occasions.