Yes, twist and lock can be done on relaxed hair. The process is similar to that of natural hair, but there are a few key differences. First, it is important to make sure your relaxed hair is well moisturized before beginning the process. This will help keep your locks from becoming dry or brittle during styling. Second, when twisting the sections of your hair, you should use more product than normal for added hold and definition as relaxed strands tend to slip easier than natural ones. Finally, you may want to consider using a leave-in conditioner or oil after styling in order to ensure your locks remain soft and hydrated throughout the day. With these tips in mind, you can easily enjoy gorgeous twist and lock styles with beautiful results!