The 50-year-old died at the scene, just after midnight.
A Foreign Office spokeswoman said they were supporting the family of a British man who died in Thailand.
Lt Col Somboon Ua-samanmaitree of the Thai Tourist Police said: "Around midnight, Mr McLaren attempted to light up a large firework but it failed to go off at first. After that, it suddenly exploded and killed him at the scene."
Police said Mr McLaren, who was originally from Corby in Northamptonshire, had visited Thailand before and arrived a few days before New Year's Eve.
According to his LinkedIn profile, Mr McLaren worked in a technical role for the International Road-Racing Teams Association.
He previously spent 11 years working for the Suzuki MotoGP team, who tweeted they were "shocked and sad" to learn of his death.
He had "remained a good friend to us all while he continued working in the paddock for IRTA", adding "we'll really miss him".
Other tributes on social media described him as "one of the most popular" members of the Grand Prix motorcycle racing community, a "great guy" and a "real professional".
Police and rescue workers arrived to find a crowd of people and Mr McLaren lying on the ground with serious facial injuries. A large firework was found at the scene.
The paper said a witness described seeing the British man celebrating New Year's Eve with friends. Mr McLaren tried and failed to light the firework before it suddenly exploded, the witness said.