be (one's) own master

To not be subject to or controlled by others, especially at work or at home. I have to be my own master, so I couldn't work in a big company like you and have to answer to a boss. Of course I'm worried about moving in with Bill—I've been my own master for a long time! In this job, you will have a lot of creative freedom. You'll pretty much be your own master.

be (one's) own mistress

Of a woman, to not be subject to or controlled by others, especially at work or at home. I have to be my own mistress, so I couldn't work in a big company like you and have to answer to a boss. Of course I'm worried about moving in with Bill—I've been my own mistress for a long time! In this job, you will have a lot of creative freedom. You'll pretty much be your own mistress.

be your own ˈmaster/ˈmistress

be free to make your own decisions rather than being told what to do by somebody else: There’s no point trying to tell him what to do. He’s his own master, as you know.