Actors Jean-Claude Van Damme, Kevin Costner and Hilary Swank all participated in the festivities, which were televised live and were officially decreed to be held for the opening of new skyscraper complex, Grozny-City.
Violinist Vanessa Mae also performed at the glitzy gala that was to culminate with a fireworks display.
The swaggering leader, whom critics accuse of megalomania and heavy-handed tactics, had banned bureaucrats from celebrating his birthday on pain of being fired, so the events in the former war zone of Chechnya were tied to the city day as well as a national teachers' holiday and a "day of Chechen youth."
A former insurgent, Kadyrov took power in Chechnya after his father, Akhmat Kadyrov, was killed in a bomb attack as he attended a Victory Day concert in the volatile region in 2004.
His critics say Kadyrov runs Chechnya as his personal fiefdom and enjoys carte blanche and hefty financial assistance from the Kremlin in exchange for loyalty.
Even though the Russian authorities remained conspicuously silent on the matter, Kadyrov's spokesman Alvi Karimov told AFP that his patron received phone calls with birthday wishes from both Russian Prime Minister Vladimir Putin and President Dmitry Medvedev.
In unprecedented security measures in Chechnya, where the Kremlin waged two wars with separatists in the past 20 years, authorities closed the main highways leading into Grozny on Monday and police carried out document checks on residents of all apartment blocks in the past two weeks.
International flags and banners bearing birthday wishes from residents festooned the main streets of Grozny, substantially rebuilt after the two separatist wars.
Numerous stars were invited to participate in the birthday celebrations, with Colombian singer Shakira, reportedly hired to perform, but she denied this on Twitter, saying she was never booked for the event.
Kadyrov said in a live televised interview Tuesday that human rights activists warned Shakira against coming.
Local media said celebrities were handsomely rewarded for attending the celebrations, with British violinist Vanessa-Mae rumoured to have received half a million dollars.
Ramzan Kadyrov as a public figure... ...and in his privacy in Tserentoi
Human rights activists accuse Kadyrov of presiding over a personal militia that carries out rampant rights abuses, torture and even murder.
Often photographed with luxury cars and the owner of a string of racehorses, Kadyrov has sought to draw positive publicity for Chechnya by inviting international celebrities.