Henson, 30, admitted drinking on the flight home after the team suffered a 31-3 defeat to Glasgow Warriors the previous night and apologised for causing offence to members of the public, airline staff and passengers.
"The Cardiff Blues management have discussed the matter at length but have acted swiftly since the incident occurred," chief executive Richard Holland said in a statement.
"Gavin admitted himself his behaviour was totally unacceptable and the immediate termination of his contract sends out a clear message that behaviour like that will not be tolerated at the Blues.
"We have a duty to our supporters and sponsors to protect the good name of Cardiff Blues and those associated with our brand."
Henson, who missed last year's World Cup with a wrist injury and played no part in the 2012 Six Nations, joined the Blues in October after being released by French club Toulon.
He was interested in signing a new deal with the French Top 14 team but was suspended last April after unconfirmed media reports that he had fought with a team mate.
