Mapa got his first professional break when he was cast to understudy, and then replace B.D. Wong in the Broadway production of M. Butterfly. Mapa later played the role on the national tour. Mapa would return to Broadway in an adaptation of L'Hôtel du libre échange by Georges Feydeau and Maurice Desvallières, re-titled, "A Little Hotel on the Side" in 1992. The next year, Mapa was back on Broadway in a Stratford Festival inspired production of Timon of Athens. Off-Broadway, Mapa earned a nomination at the 2001 Lucille Lortel Awards for his performance in the Jessica Hagedorn play Dogeaters, and was featured in every play in the "Whitelands" trilogy, a series of plays about gay Asian men written by Chay Yew; "Porcelain" (1992), "A Language of Their Own" (1995), and "Wonderland" (1999).
On television, he has made guest appearances on a wide variety of programs, including The Jamie Foxx Show, Roseanne, Seinfeld, NYPD Blue, Friends, Murder One and Dharma & Greg. He had a supporting role in the short-lived 2001 comedy Some of My Best Friends. He played Adam Benet in the UPN comedy Half & Half.
Mapa was a featured performer on the Logo original stand-up comedy series Wisecrack. In 2006 appeared as Vern, Gabrielle's personal shopper, on the TV series Desperate Housewives. He had a recurring role on the 2006-2010 series Ugly Betty, as Suzuki St. Pierre, the flamboyant host of a fictional gossip and news show (who, it is revealed, is actually a straight—and married—journalist named Byron Wu). He performed the voice of Rick's flamboyantly gay uncle Bakla on the 2007-2009 animated series Rick & Steve: The Happiest Gay Couple in All the World.
Mapa is gay and lends his support to various projects supporting the gay, lesbian, and Asian American communities. In 2008, Mapa legally married Jamison 'Jamie' Hebert, after dating since 2002. On the TV series The Gossip Queens, Mapa stated in the opening episode that he and his husband had recently adopted a 5-year-old boy. Mapa is Filipino American.
Mapa also performed on the 2009 Atlantis Freedom Caribbean Cruise headlining in the Arcadia Theater.
In 2010, Mapa became one of the co-hosts of Logo's The Gossip Queens, a daily series where he helps present Celebrity gossip.
