DUP Foyle MLA Gary Middleton is taking on a new temporary role within the Stormont Executive.
It comes after DUP Environment minister Edwin Poots has had to step down from the Executive to undergo surgery.
Last month, Mr Poots revealed he had been diagnosed with a cancerous growth on his kidney.
East Antrim MLA Gordon Lyons has been nominated as his replacement.
Mr Middleton will take over Mr Lyons’ responsibilities as junior minister.
First Minister Arlene Foster said the change was only temporary, to allow Mr Poots to recuperate from surgery.
“We give Edwin our best wishes and assure him and his family of our prayers.”
Mr Middleton tweeted a picture of himself today, saying: “Officially signing the pledge of office this morning before taking up the post of Junior Minister in the Office of the First Minister.
“Humbled to be bringing a voice from the North West to the table.”