Use the three-needle bind-off when you’re joining stitches head to head. The three-needle bind-off is the quickest and easiest joining method in knitting, and it creates a stable (and visible) seam.
For the three-needle bind-off, you need three needles: one each to hold the shoulder stitches and one for working the actual bind-off. If you don’t have three needles of the same size, use a smaller one for holding the stitches of one or both of the pieces to be bound off, and use a regular-size needle for binding off.
Thread the open stitches of your pieces onto a needle — one for each piece.
If you’ve left a long tail end (about four times the width of the stitches to be joined), you can use it to work the bind-off.
Thread your first needle through the stitches on the first piece.
Make the point come out where the tail is.
Thread the second needle through the second piece.
Make sure your needle tips will point in the same direction when your pieces are arranged right sides together. If you haven’t left a tail end for this maneuver, you can start working with a fresh strand and weave in the end later.
Insert the third needle knitwise into the first stitch on both needles.
Position the needle as if you were knitting both stitches.
Wrap the yarn around the RH needle as if to knit and draw the loop through both stitches.
Knit the next pair of stitches together in the same way.
Using the tip of either LH needle, go into the first stitch knitted on the RH needle and lift it over the second stitch and off the needle.
Continue to knit 2 stitches together from the LH needles and bind off 1 stitch.