Pellegrini has overhauled West Ham's squad this summer breaking the club's transfer record to sign Felipe Anderson from Lazio while signing Jack Wilshere, Fabian Balbuena, Andriy Yarmolenko, Lukasz Fabianski, Ryan Fredericks, Issa Diop and youngster Xande Silva.
The 29-year-old joined the Hammers after spending two years on loan with Deportivo La Caruna since 2017.
The Mexico global scored just eight goals in 28 league appearances last season but is looking forward to working with Pellegrini.
Duncan Castles: FC Barcelona defender open to signing for Man United
Barca had hoped to sell him permanently but initial interest from Arsenal and Valencia failed to materialise into a serious offer. Yerry Mina is open to a move to Manchester United before Thursday's transfer deadline, according to reporter Duncan Castles.
West Ham have confirmed the signing of Colombia global midfielder Carlos Sanchez from Fiorentina.
The new season is right around the corner and, inevitably, that means changes to the schedule will occur for every Premier League side - and West Ham have today learned that two of their fixtures in October and November have been moved for TV coverage.
Perez cost Arsenal a reported £17million in 2016 but made just two Premier League starts under Arsene Wenger as he failed to earn a regular spot at the Emirates Stadium.
André Gomes credits Silva as major factor in signing for Everton
He has signed a five-year contract and joins Lucas Digne , the left back who also moved from the Nou Camp this summer. Mina , who was linked with a move to Manchester United , joins the Toffees on a permanent deal worth €30.25 million.
"I'm very motivated." Perez said. "I'm very excited and looking forward to achieving lots", Sanchez told the club's website. "I chose to come here because, first, it is the Premier League, second, it's a attractive club and the fans are always helping the club and, third, for me it's an unbelievable opportunity and an incredible project the club are leading, being ambitious and keen to achieve good things".
Perez managed to score eight goals in 35 matches for Deportivo who have been relegated into the Segunda division in Spain last season. The former Chelsea youth player signed a four-year contract with the Hornets.
North Korea will preserve know-how despite denuclearisation: Foreign Minister
Washington has said that sanctions will not be lifted until Pyongyang fully and finally dismantles its nuclear weapons. In this image captured from the United States Forces Korea homepage, an official from the U.S.