He played for the Columbus Landsharks, Arizona Sting, Minnesota Swarm and Toronto Rock.
As a rookie, Beirnes made the 2002 National Lacrosse League all-rookie team as a member of the Landsharks.
On June 23, 2005, Beirnes and Darryl Gibson were traded to the Minnesota Swarm in exchange for two first round draft picks.
Beirnes was traded from the Swarm to the Toronto Rock in exchange for two picks during the 2008 draft.
In 2013 and 2014, Beirnes was a member of the Six Nations Chiefs, who won the Mann Cup.