Former premier Mike Rann has finally revealed his future, confirming he's officially retiring from politics this Friday.

That'll mean a by-election in his seat of Ramsay on February 11, the same day the people of Port Adelaide choose a successor to Kevin Foley.

Mr Rann says he's been keeping a low profile over the last few months, and being a support to his wife Sasha who's battling breast cancer.

"There's been hospitals and clinics and things, it's given me the chance to give her some support. I've just been working at parliament house or my electorate office in Salisbury."