Doumbia moves to St. James’ Park until the end of the season, with an option to make the deal permanent in the summer.
He signed for Roma in January 2015 before being loaned back to CSKA Moscow last August.
“I’m delighted to be a Newcastle United player. I’ve already started to prepare. I’ve arrived and I’m ready to go. It has always been a dream to play in the Premier League and now that dream has come true, so I’m absolutely delighted. I am looking forward to helping the Club get some wins and climb the table,” said Doumbia.