The Australian actor said that he was struggling to make headway in the casting race for the Marvel hero until his Cabin In The Woods producer Whedon recommended him to Thor helmer Kenneth Branagh.
The Coventry Telegraph quotes Hemsworth as saying: "Joss is fantastic. I worked with him on Cabin In The Woods. He wrote and produced it with director Drew Goddard.
"Right back when I was shooting Cabin In The Woods there was the casting for Thor. The process was ending and he said, 'Why aren't you involved in it?' and I said, "Well I was earlier, but I've been in and out of it - What's going on?' And he said, 'I'll give Ken a call,' and he called Ken Branagh.
"They didn't know each other but knew of each other and Joss said, 'Look, for what it's worth, I've been working with Chris and he's a good bloke'."
The actor added that Whedon's call helped him get "back in there" and secure the part of the Norse god banished to Earth.
Hemsworth and director Whedon will reunite on Marvel's ensemble superhero picture The Avengers, opening in cinemas in May 2012. Thor will debut in the UK on April 27 and the US on May 6.