The Belgian international, who had been turning out for Olympiakos for the past two seasons, had been heavily linked with a move to Everton's Premier League rivals Arsenal.
However, the 24-year-old has revealed that a combination of manager David Moyes and the promise of a place in the starting lineup lured him to Goodison Park.
"From the word go, I was really impressed by the extent to which the manager wanted me [at Everton]," he told reporters.
"What's important for me at this stage in my Premiership career, just about to embark in a new league, is to get plenty of time on the field.
"And I think that I had a possibility of playing in more games, and for longer periods, with Everton."
The centre-forward could make his debut during Saturday's trip to Aston Villa.