Keller received a masters degree in Interactive multimedia from the Tallinn Art Academy in 2002. Since 2000, he has been engaged in a multitude of contemporary art practises, focusing on site-specific sound installations, performance, improvisation, DIY culture, video- and radiphonic art. His site-specific group improvisations, which began in 2000 as Project Unison, have been released on five CDs.

Founding member of MKDK, a “dynamic collective of music and arts”, Keller also performs in his burlesque Americana group The Great Outdoors as Paul Cole, a fictional rock artist who released albums in 2004 and 2009. In 2009 his first solo album Me tuleme kaugelt/We Come from Afar was released on MKDK Records, and contained excerpts of commissioned work from 2004–2009.