Moyes told evertonfc.com: "He has a very good goalscoring record in the Premier League and he also offers strength and power. We hope he continues his good scoring record with us.
Nigeria international Yakubu told evertonTV: "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.
"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."