Sevilla have strengthened their attack with the addition of Javier 'Chicharito' Hernandez from West Ham on a three-year contract.
The Mexico international underwent a medical before becoming the club's 12th summer acquisition.
Sources told ESPN FC the transfer is worth €8 million.
"I want to thank West Ham for being open to negotiate and allow me to leave," Chicharito told a news conference on Monday. "It was not easy and it was completed late in the transfer window. I know Sevilla have put a lot of confidence in me. I'm going to give my all. I need to prove that on the pitch.
"I hope that this new chapter in my career is better than my previous spell in La Liga. I feel well, I feel 100% and I've returned to my national team.
"I want to show my best and I see myself scoring a lot of goals. This is a step forward in my career and it gives me a lot of enthusiasm. I feel I'm in the best form of my career and I just want to continue to grow as a player and as a human being."
He handed in a transfer request last week and arrived in Seville on Sunday.
"Few times have I spoken to a player and he has transmitted the enthusiasm in our project as Chicharito has done when I first spoke to him," Sevilla sporting director Monchi added.
"I've never seen a player cut his wages the way he has done in order to come here. That's a sign. He has made an important financial sacrifice to come here and when I think about that, I realise it can only be down to his true desire to play for Sevilla. I think he is among the best strikers in the world. Javier has goals, has quality, he is fast and he is a good finisher."
Chicharito returns to La Liga, having previously played for Real Madrid on loan from United in the 2014-15 campaign.
He joined West Ham from Bayer Leverkusen in July 2017 in a £16m transfer and scored 17 goals in 63 club appearances.
Mexico's all-time top scorer with 51 goals in 108 games, Chicharito will travel to the United States in the next 24 hours to join his national team ahead of the upcoming international friendlies against the U.S. and Argentina.