The Office creator reprised his cringeworthy character from the hit comedy and performed with fake band Foregone Conclusion at the Bloomsbury Theatre in the U.K. capital.
There was another famous face in the line-up as well - former Razorlight star Andy Burrows was on percussion.
As his alter-ego, Gervais performed 10 tracks, kicking off with Free Love Freeway, one of the songs which he performed during the first series of the British sitcom in 2001.
Fellow The Office star Ewen MACIntosh, who played boring Keith Bishop, introduced Gervais to the stage.
The second show will take place on 23 October (13). Tickets for the gigs sold out in less than one minute, with touts trying to resell them for as much as $1,500 (£1,000) online.
Gervais was left disgusted by the ploy, and urged fans not to shell out thousands for tickets which originally cost less than $30 (£20).