[2][3] In 1979, Rongen moved to the United States, joining the Los Angeles Aztecs of the North American Soccer League.

On 8 January 1988, he became the first player to sign with the Fort Lauderdale Strikers of the newly established American Soccer League.

Rongen began his coaching career as an assistant with the Pope John Paul II High School boys' team in 1984.

[16] He took the Strikers to the 1989 ASL title and then skippered the team to a victory over the San Diego Nomads in the national championship game.

[21] On November 5, 1996 the New England Revolution traded their first-round pick in the 1997 MLS College Draft to the Tampa Bay Mutiny in exchange for the right to hire Rongen as their new head coach.

[22] Rongen coached the Revolution to their first-ever playoff appearance in the 1997 season,[22] but was unable to replicate the success he had in Tampa Bay.

[22] Following his two year stint with the Revolution, Rongen succeeded Bruce Arena as the head coach of D.C. United, which he led to the Supporters' Shield and MLS Cup titles in 1999.

However, ten games into the season, with the team's record standing at one win, one tie, and eight losses, he was let go of his head coaching duties.

With Rongen at the helm, and after three weeks training them both physically and inspirationally, American Samoa registered its second ever victory on 22 November 2011, against Tonga, in the 2014 World Cup qualification.

His work with the American Samoa team is at the center of the 2014 British documentary, Next Goal Wins[28] and the Taika Waititi directed film of the same name, starring Michael Fassbender as Rongen.

Rongen became director of TFC Academy prior to the 2012 season, joining countrymen Aron Winter and Bob de Klerk at Toronto FC.

[31] In late 2016, Rongen was hired by Bruce Arena as the head international scout for the United States national team program.