Metcalfe moved to Los Angeles and attended an open casting call, successfully auditioning for the NBC soap opera Passions. He played Miguel Lopez-Fitzgerald, one of five siblings, from the show's debut in July 1999 -July 2004. He left Passions because he felt that he "wasn't really going to get anything more out of it."

In late 2003 and early 2004, Metcalfe made two guest appearances on the WB Network TV series Smallville as vindictive "meteor freak hunter" Van McNulty.

Metcalfe returned to television as the teenage gardener John Rowland on the popular ABC TV drama Desperate Housewives, where his character had a secret relationship with housewife Gabrielle Solis played by Eva Longoria, since the series' debut in October 2004. This was the role that made Metcalfe a household name, and he immediately gained attention for his well-toned body, particularly his smooth and muscular pectorals, emphasised by the fact that he appeared shirtless in almost every scene he was in. US