Altering a men's suit jacket to create a dress is possible but you are limited by the shape of the original jacket. An average suit jacket will create a short dress with a deep plunging neckline. If you are purchasing a suit jacket from a resale shop for this purpose, try the jacket on and note where the top button of the jacket rests on your body. If the button is too low by your standards of modesty, you may want to find another jacket or consider wearing a shirt underneath the finished dress to avoid exposing yourself.
Try on the men's suit jacket to check the size and length. The bottom of the jacket needs to rest at the desired length of the finished dress.
Turn the suit jacket inside out and put it back on. Button the front of the jacket.
Pin the front and back of the suit jacket together very close to the sides of your body with safety pins. This process is easier to accomplish with a helper to insert the pins while you stand still. When you are finished inserting the pins, the body of the jacket should hug the curves of your body tightly while still allowing you to move comfortably.
Remove the jacket, leaving all of the pins in place.
Sew a seam on each side of the inside-out suit jacket, just along the outside of the line of safety pins, with a sewing machine and thread matching the fabric of the suit jacket.
Remove the safety pins and turn the jacket right-side out.
Remove the sleeves from the suit jacket with a seam ripper. Carefully pry the stitching loose until the sleeves are completely removed; this process is time consuming but be patient to avoid tearing the fabric of the jacket.
Trim any loose thread from around the arm holes. Fold the edge of the arm holes inside the jacket and whip stitch with thread of the same colour as the suit jacket to give them a neat appearance. You may also sew a piece of lace seam binding around the edge of the hole to add decoration.
Sew a hook and eye closure to the bottom hem of the dress to keep the bottom front of the dress together while you are wearing it. Attach the hook to one side and the eye to the opposite side while you are wearing the dress to ensure proper placement. Hand sew the closure in place.