The Portuguese joined the Hammers in January 2012 and scored 12 goals before the end of the season to propel the team to the Premier League.
And that haul included a late winner in the play-off final victory against Blackpool at Wembley.
But the 28-year-old has found appearances harder to come by in recent seasons and he has played just five times this season for West Ham.
While Vaz Te concedes leaving the club has been a difficult decision, he departs with happy memories of his time in east London.
“It has been a pleasure to be at a club like West Ham. It was a fantastic opportunity and I am so grateful for having played here,??? Vaz Te said.
???Everything I achieved here and all my game time and my life off the pitch has been amazing.
“I will never forget that day at Wembley – it was so special for me and for all of the fans involved.
???That is the kind of moment you don’t intend to forget. I’m very fortunate to have had that moment and I’m pleased I could do that for the fans, for the club and for my team-mates.
“I would like to thank the West Ham fans and to tell them to keep supporting the club through what is going to be an exciting time over the next few years.”