Kids in Glass Houses, Guillemots and Skindred have also joined the longlist for the event at Hyde Park from July 13-15.
The London festival will see headlining sets from Soundgarden, Bruce Springsteen and Paul Simon, who will perform his Graceland album in full.
Black Stone Cherry and Marcus Foster have also been added to the lineup.
Amy Macdonald will release her third LP Life in a Beautiful Light on June 11.
The lineup for Hard Rock Calling so far is as follows:
Bruce Springsteen And E Street Band
Black Stone Cherry
Kids in Glass Houses
Life In Film
Gary Clark Jr.
Robert Randolph & The Family Band
Listen to Amy Macdonald's new single 'Slow It Down' below: