The US band performed at London's Hyde Park and their frontman Caleb Followill told the crowd to raise a glass to 'a friend of ours who's passed away', according to NME.
They then said 'this is for Ryan' before playing their track McFearless.
The Jackass star was recently killed in a car crash and bassist Jared Followill had written a message on his Twitter page paying tribute to him.
He said: 'I'm heartbroken to say that our great friend we made over the last 8 months has passed away. Honestly in shock. Devastated. RIP Ryan Dunn.'