Elyounoussi is a Norway international – he has 22 caps – and was a big summer recruit at St Mary’s last year when he made the move from Swiss side Basel. The 25-year-old made 19 appearances for Saints but has not featured at all for Ralph Hasenhuttl’s team so far this season.
Early in his career Elyounoussi played for Sarpsborg and Molde in his homeland, and he has already scored at Celtic Park – when Molde beat Celtic home and away in the group stages of the 2015-16 Europa League, Elyounoussi scored in both games.
“I can’t wait to get started and pull on the jersey for the first time,” Elyounoussi told Celtic’s website. “It’s an iconic, historic club so it’s a great move for me.
“This is something I want to achieve at Celtic, scoring goals and creating chances to help the team win games and winning titles.”
Meanwhile, Neil Lennon has confirmed his interest in Kilmarnock’s 21-year-old left-back Greg Taylor.
“We’re looking for a left-back,” said the Celtic manager. “There are a number of options and Greg would be one of those.”