Simon Mitchell was taking photos of a race but was fatally wounded by a bike when the rider fell off during a race in Foxhill Motocross in Swindon on Sunday.
The bike left the track smashing into Mr Mitchell, in his 50s, and a marshal in his 60s at around 2.50pm.
The marshal was taken to hospital with a serious injury but is expected to survive.
The third round of the Revo ACU British Motocross Championship was called off following the tragedy.
The rider was not hurt in the crash at the end of the Premier Class Race.
A Wiltshire Police spokesman said: “At around 2.50pm yesterday, we responded to an incident at Foxhill Motocross in Swindon involving a rider and two members of the public during a race.
“The rider was dismounted following a jump and the unmanned bike has left the track, sadly killing a man in his 50s.
“His next of kin have been informed and our thoughts are with his friends and family at this time.”
A spokesman for the Foxhill track posted a tribute to Mr Mitchell on Facebook.
It read: “The entire team at VMXdN Foxhill is deeply saddened by the passing of Simon Mitchell yesterday afternoon (May 14th) following a freak accident trackside.
“Simon was a brilliant photographer, a huge motocross enthusiast, and an incredible supporter of VMXdN Foxhill from day one.
“Simon worked closely with the VMXdN team for many years within our different roles in the MX industry. Over the years, he has captured many memories that will be forever cherished.
“Many of Simon’s photographs are displayed across our social pages and website. His photograph was the original image behind last year’s Mike Brown Merch T-shirt, which he was incredibly proud of. Simon was a genuinely lovely guy who always had time and wanted to help others.
“We know he will be so sadly missed by the whole VMXdN Team and the motocross community.
“Our thoughts and condolences go to his family and friends at this very sad time.”
Foxhill, considered one of the best motocross tracks in the UK, is famed for its steep turns and jumps.