The masculine version:
Dominus tuus es tu ipse.
Dominus is usually translated "lord", but it means master, especially a slave-owner. Literally, the sentence means "Your lord is you yourself." Tu ipse is the standard formula for putting the emphasis on "you" like this.
I'm not sure why I think it works better in Latin to reverse the order of the nouns from English. Maybe it's because, as I understand the original, it aims to lead the listener to stop thinking of him- or herself as a slave. So, in the typically Latin way, we start with the current understanding and move to the new, by in effect answering the question, "Who is your lord?"
You could also say est (3rd person, "is") but I think es (2nd person, "art") is stronger. Est makes dominus tuus the subject and tu ipse the subject complement. Es makes tu ipse the subject and dominus tuus the subject complement—reversing the prosaic word order, emphasizing the idea that you, not someone else, are in charge.
It's amazing how much expressiveness you can get from Latin's grammar and free word order! But you can do exactly the same in archaic modern English: "Thy lord art thou thyself" (as opposed to "Thy lord is thou thyself").
For the feminine version, you could have either of these:
Dominus tuus es tu ipsa.
Domina tua es tu ipsa.
The second means "Your lady is you yourself." Domina means primarily "the lady of the house". In Roman society, the master of the house would nearly always be male, so the first version might better fit "Thyself is thy master." Perhaps it's even stronger for the clash of genders.