Mike Freeman was said to have collapsed less than a mile from the finish line, according to local newspaper reports.
Paying tribute on Facebook, his wife Nicola told of her devastation and said Mr Freeman, who was part of a local running club in Essex, had a passion for the pastime.
Writing on the Facebook page of Michelle's Running Group, she said: "He loved running and he loved you all. One of our last words were about running up to the finish and how lovely it would be to see you all there. He joked 'Next year eh!' Devastated."
Michelle Caulfield, leader of the group, said their usual running sessions would go ahead to allow people to come together to remember him, and many members suggested making donations to charity in Mr Freeman's memory.
Media reports in Malta said a doctor had given Mr Freeman, believed to be 55, the all-clear to participate in the race after he had complained of chest pain two weeks ago.
Parents of pupils at Notley Green Primary School in Braintree, where Mr Freeman was a member of staff, said he would be sadly missed.
One wrote: "My boys have often spoken of Mr Freeman and commented how much they liked him. He will be missed. Sending my condolences to his family."
Another said: "Terrible news, my daughter speaks of Mr Freeman often and I know that she and all the children at Notley Green will miss him terribly."
A Foreign and Commonwealth Office spokesman said: "Our thoughts are with the family of a British man who died in Malta on February 28.
"We stand ready to assist them at this difficult time."
A post-mortem examination is due to be carried out on Monday.
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