The switch, part of a long-awaited Cabinet reshuffle by May, comes almost a year to the day since the collapse of the once-troubled province's semi-autonomous government.
After undergoing several tests, Mr Brokenshire has been informed that he has a lesion in his lung which needs to be removed. Bradley made little impression at first, either on the arts world or on the other parts of her brief covering "digital, culture, media and sport".
Brokenshire, 50, took to Twitter later in the day to express his appreciation for messages of support.
Mr Brokenshire added that following his surgery, his main focus will be on recovery and getting back to his role as MP for Old Bexley and Sidcup at the earliest opportunity. It is now a year since Northern Ireland has had an effective, functioning power-sharing administration, and forming a Northern Ireland Executive, to deliver for the benefit of all, is my top priority.
Following the breakdown of talks, the province is on the brink of direct rule by civil servants in London who have already been managing its budget.
In her choice of Karen Bradley as Northern Ireland secretary, Theresa May has replaced one of her former junior ministers at the home office with another.
Talks are still stalled on two key demands from Sinn Fein, which backs the legalisation of same-sex marriage and legal protection for the Irish language.
The British and Irish Governments had been expected to kickstart another bid to restore devolution after several rounds of talks previous year failed to produce a deal between the DUP and Sinn Fein.