Mr Poots said the Stalford family had asked him to take over the seat in the south of the city.
Speaking at lunchtime outside Christopher Stalford’s constituency office in Sandy Row, Mr Poots said: “This is a day where I stand here with a lot of regret having lost a good colleague and friend. And I am standing here out of necessity more than anything else.
“Last week Christopher’s family spoke to me and asked me if I would consider taking on the role of MLA for South Belfast. And it’s on that basis that the party asked me to take on this responsibility.”