He is best known for his roles in television shows including Sabrina the Teenage Witch, Trinkets, Moesha, Party of Five, and 7th Heaven and in films such as 10 Things I Hate about You (1999), The Broken Hearts Club (2000), and O (2001).

That same year, he landed a recurring role on 7th Heaven, where he played a single teenaged father in love with Jessica Biel's character Mary.

Keegan then took a role in Greg Berlanti's ensemble film The Broken Hearts Club: A Romantic Comedy (2000), which won Best Picture that year at the GLAAD Awards.

In 2014, Keegan founded Full Circle, a community spiritual center based in Venice, Los Angeles.

[6] In a 2015 interview, Keegan described the group as a "non-denominational spiritual community center where people of all beliefs and backgrounds come together to meditate, practice yoga, and engage artistically.

"[7] New York Magazine reported in March 2015 that "the actual theology of the group is tough to pin down, but it seems to loosely follow Hinduism—or at least Russell Brand's Sanskrit-tattoo version of it.