The actor has recurred as Crowley since Season 5, appearing in 35 episodes of the series since 2009. The character played a major part in the show's Season 9 finale, "Do You Believe In Miracles?", which ended with Dean (Jensen Ackles) being turned into a demon under Crowley's watch.
Misha Collins, who plays the fallen angel Castiel, was also promoted to series regular earlier this week. The actor had previously recurred in Season 4 and Season 8, and was a series regular in Season 5, Season 6 and Season 9.
The show was given an early renewal for Season 10 back in February. The CW also ordered a spin-off series, Supernatural: Bloodlines, to pilot, but the network passed on the show earlier this month. The network is entertaining other spin-off possibilities at this time.