Everton have completed a club record £11.25m deal for Middlesbrough's Yakubu after he was granted a work permit.
Yakubu becomes Everton's record signing
Yakubu, 24, was initially refused a permit because he failed to play 75% of Nigeria's games in the last two years.
But Everton won an appeal and the striker has signed a five-year deal at Goodison Park after agreeing terms and passing a medical.
He is second only to Thierry Henry in the Premier League goal charts over the last four seasons.
Yakubu told Everton's website: "I am happy to be here. It is a great feeling to come over and meet a lot of good players and see the spirit that they have.
"I have always said that I want to play for a club that plays in Europe and I think they have the ambition to move forward and they want to finish in the first four and the Champions League and Uefa Cup and for me that is my dream."
"I know there is a long way to go and I want to be part of that - to be successful and to have that dream.
He added: "I chose to go to Middlesbrough because they were in Europe. At the moment they are not doing it.
"I think I made the right decision to come to this place. It is a massive club and it is a great feeling. There are great players and you want to play for a big club."
Portsmouth were also said to be interested in re-signing Yakubu, who they bought from Maccabi Haifa in 2003, before selling him to Boro two years later for £7.5m.
He clocked up 29 goals in 65 Premier League games at the Riverside.
Yakubu featured in Boro's opening two Premier League games of the season but missed the next two games against Fulham and Newcastle.