He arrived in the Senate chambers with former Sen. Peter Fitzgerald and Sen. Dick Durbin. Roughly 90 friends and family were also in attendance.
Kirk said he doesn't plan to do too much during his stint in the lame-duck session.
"I think we should make limited decisions," Kirk said Monday morning on MSNBC's Morning Joe. "And allow the fresh congress that the American people elected with a mandate make the big decisions."
He'll have to cast votes on at least two important initiatives, however, when a bill sponsored by Illinois' other senator, Dick Durbin comes up for vote. Kirk will be asked to vote on a food safety bill that would give the FDA more power to prevent E. coli contaminations.
Shortly after he'll be asked to vote on whether to renew the Bush tax cuts, which are set to expired on Dec. 31.
The senator-elect details some of his other voting initiatives in an interview with the Chicago Sun-Times.
Republicans will now have 42 votes in the Senate, a number that will rise to 47 in January.