Steve Ralston will continue as interim head coach for the final two matches of the 2018 season.
Almeyda, 44, was hired as Chivas de Guadalajara manager in September 2015 with the club drifting into a relegation battle. He reversed Chivas' fortunes, guiding them to the 2017 Clausura Liga MX title, and winning two Copa MXs, and the Supercopa MX. He also oversaw Chivas' 2018 CONCACAF Champions League final success over Toronto FC before stepping down in June.
Prior to his job in Mexico, the 35-time Argentinian international made the transition into management in 2011 and immediately steered South American giants River Plate back into the country's top flight. He took over fellow Argentine outfit Banfield in 2013 and repeated the trick of instant promotion into the Primera Division before earning qualification for the 2016 Copa Sudamericana.
Almeyda had a journeyed playing career that saw him collect three Argentinian championships, one Copa Libertadores, one UEFA Cup Winners' Cup, one UEFA Super Cup, three Italian Cups, and one Serie A title when with Lazio.
"He has always had a winning mentality, both as a player and a coach, and most importantly, he is someone that knows how to redirect a team in a difficult situation with a commitment to a distinct style of play and youth development," general manager Jesse Fioranelli said.
"Matias came here because he welcomes the challenge of helping our organization open a new chapter after a grueling season. He had several other opportunities available to him from clubs and national teams around the world but made it very clear the Earthquakes were the one he wanted to lead."