This week Shanghai Shenhua agreed to extend Ighalo's loan deal until January 31.
"We've already had some really good news at United this week with Odion extending his contract," Shaw told United's official website. "All the players are really happy for him.
"Obviously his situation was up in the air and we try not to talk about that kind of thing at training but we're just so happy for him.
"Before he arrived, a few people outside the club weren't too sure what he was going to bring to the club, but he's shown everyone because he's brought goals and a different style to our other strikers.
"He's earned and deserved the chance to stay here longer. He brings happiness and a smile to the place. He's great in training but he's also been really important at times during games and scored some great goals.
"Now that everything's sorted, hopefully he can relax now and settle back into doing what he was doing before football stopped."