The American actor, who plays wheelchair-bound Artie in the Fox musical comedy, praised the divers for putting in spectacular performances after having "overcome so much" in their personal lives.
"Love the Olympics & how people overcome so much to perform brilliantly for their country," he wrote on Twitter. "@Tomdaley1994 @chrismears93 these dudes!!"
Daley was left heartbroken by the death of his father in May 2011 after a long battle with cancer.
The sportsman's dad was referenced in a series of abusive messages left by a Twitter user after his fourth place finish in the synchronised diving on Monday (July 30).
Mears, meanwhile, suffered a ruptured spleen in 2009 and was given less than a 5% chance of survival after losing five pints of blood.
McHale has been keeping up on the Games from the US, but he recently admitted to having trouble avoiding event spoilers due to the time difference.
"This whole thing w/ certain Olympic events being delayed until primetime is terrible. gotta stay off of the internet for another week," he wrote, before adding later: "Accidentally found out the results to almost every event airing tonight."
Daley has received support from other celebrity fans including Cheryl Cole, while President Barack Obama and Justin Bieber recently sent congratulatory messages to US Olympians Michael Phelps and Missy Franklin respectively.
Photo gallery - London 2012 Olympics:
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