The Nigerian striker triggered the buyout clause from his contract by Levante, the Spanish top-flight side confirmed on its official website Monday, paving the way for the lengthy courtship between the Sounders and the player to wind up with him joining MLS.
Martins himself took to Twitter to say that he has signed for Seattle, writing, "Wow..Finally,I can now announce that I have just signed for Sounders FC..A big step to take in my career.it's a big challenge but I'm ready.
"I look forward to this new era in my career... I also look forward to meet my new teammates and the Sounders FC fans, my new family..."
Seattle has yet to confirm the signing, and Goal.com has attempted to reach the Sounders for comment.
The 28-year-old Martins has scored nine goals in all competitions for Levante this season, and he played 90 minutes in the UEFA Europa League against one of his former sides, Russian outfit Rubin Kazan, on Thursday. Expected to sign as a Designated Player to fill Fredy Montero's shoes, his partnering with Eddie Johnson will allow Mauro Rosales to slide back into a midfield role after he started as a forward in the club's season-opening loss to Montreal and CONCACAF Champions League loss to Mexican side Tigres UANL.