The talented striker, 20, was loaned out by Chelsea on deadline day, learning of the potential move at 7pm (UK time) on Monday.
Lukaku came off the bench twice for the Blues early in the English Premier League season and was introduced in extra-time against Bayern Munich in the UEFA Super Cup, where he missed the decisive penalty in his team's loss.
Everton are 20/1 with William Hill to win the FA Cup
"For my development and with the World Cup coming up at the end of the season, I cannot afford to stay on the bench," Lukaku said while on international duty.
"At Everton, I can continue my progress in a club that likes to play beautiful football."
Kind words from Everton manager Roberto Martinez convinced Lukaku, who scored 17 league goals on loan at West Brom last season, to make the move.
"I wanted to know certain things before I agreed. When you are on loan, you have to know that you are really going to play," Lukaku said.
"Then I received a call from Roberto Martinez and he reassured me and said lots of nice things. And Kevin Mirallas was in my room with me almost the whole time. He told me how things worked at Everton and he encouraged me to come."
Blessed with one of the best squads in the Premier League, Chelsea added Samuel Eto'o to their striking ranks during the transfer window.
But Lukaku, who also attracted interest from Malaga and West Brom, said the arrival of the Cameroonian had no impact on his decision.
"I had some doubts about the game time I would get. At my age, I absolutely have to play. The arrival of Samuel Eto'o had nothing to do with it," the powerful forward said.
"(Chelsea manager) Jose Mourinho called me and he was clear with me. It is better like that. I like it when a coach is honest.
"He is the best coach I have had. He wanted to make me better and did it with a firm hand. We agreed that a loan was the best solution."