Alex Attwood is to be Northern Ireland's new Social Development Minister in the first of a string of post-General Election changes at Stormont.
Mr Attwood will take over from party leader Margaret Ritchie, who is stepping down from the Executive following her election as South Down MP last week.
Meanwhile, the DUP has made clear it intends to end double-jobbing within “weeks”.
That means a new Finance Minister will have to be appointed to replace Sammy Wilson.
Mr Wilson has been re-elected as MP for East Antrim and in common with senior party colleagues will be quitting the Assembly to concentrate on that role.
The list also includes DUP deputy leader Nigel Dodds, Jeffrey Donaldson, Gregory Campbell and the Rev William McCrea.
Comments made by Mr Campbell yesterday on a phased approach to ending dual mandates sparked speculation about the party's intentions.
But in a statement, Mr Dodds said: “In response to some misrepresentation, I want to reaffirm and clarify that there has been no U-turn in the DUP’s position on multiple mandates. Our party officers and ruling party executive have voted to bring this practice to an end.”
Possible contenders to replace Mr Wilson include ministerial colleagues Arlene Foster and Edwin Poots, and DUP MLA Simon Hamilton.
The SDLP says that Mr Attwood will take over the Social Development job as soon as possible.
Ms Ritchie said: “I made a commitment that if nominated, selected and elected as MP for South Down I would stand down as Minister for Social Development.
“I wish Alex all the best in his new role.”
Mr Attwood is an MLA for West Belfast, a constituency otherwise dominated by Sinn Fein. His ministerial job will boost his profile in the run-up to next year's Assembly election.
He said yesterday: “I intend to build upon Margaret’s legacy in the department, and representing an area of high deprivation, I know exactly the amount of work there is still to do.
“Fair access to housing was one of the major civil rights issues that led to the formation of the SDLP. Margaret Ritchie has led the way in delivering her new housing agenda.”