The value of his move was undisclosed by the Hammers, although they revealed Paqueta had signed an initial five-year contract at the London Stadium with a one-year option.
Paqueta’s arrival should bolster West Ham manager David Moyes’s attacking options, with the Hammers having scored just once in their opening four Premier League games — Pablo Fornals scored the winner in Sunday’s 1-0 victory at Aston Villa.
“I am extremely happy to be here. I hope it’s the beginning of an enjoyable journey. I hope my time here is successful,” Paqueta, 25, told West Ham’s website.
“Last season, West Ham had a very good season and I hope they continue to enjoy more and more good seasons in my time at the club.”
Paqueta started his career at Flamengo, before moving to Europe when he joined AC Milan in 2019.
He then spent two seasons in Serie A but only managed one goal in 37 league outings for the Rossoneri before moving to Lyon, where he had more success with 21 goals in 80 games across all competitions while also becoming a regular in the Brazil squad.
“I’m delighted to welcome Lucas to West Ham,” said Moyes.
“He’s a player I’ve admired from afar for a very long time and of course, we saw him close up in our Europa League campaign last season.
“He’s a very talented footballer and whilst he will need time to adapt to the Premier League, we’re excited about adding another proven international to our squad.”