"It is time for me to retire and move on to other things," said Marilyn More, who was first elected to the provincial legislature in August 2003.
"It's a very intense life and very exciting. It reminds me of Charles Dickens saying, 'It's the best of times, it's the worst of times.'"
Deputy premier Frank Corbett will take over as minister of labour and advanced education. Corbett will also become the immigration minister, a job More also held.
More will remain in Dexter's cabinet as a minister overseeing four government bodies including the Public Service Commission and Communications Nova Scotia.
Dexter said he kept More in his cabinet because the "runway" to an election is diminishing.
"At this point in time in the mandate, bringing someone new in, that would be a different experience than it would have been a year ago," Dexter said.
He declined to say when he would call an election. The legislature can only continue sitting until the middle of 2014, at which point a vote must be called.
More represents the Halifax riding of Dartmouth South-Portland Valley.