Strike action planned for Christmas Eve and New Year's Eve on two Tube lines has been suspended, the Rail Maritime and Transport union (RMT) said.
The RMT said strikes were called off after the intervention of Acas
Drivers on the Hammersmith and City and Circle lines had been due to stage 24-hour walkouts over the sacking of a colleague.
The man was dismissed after he was seen leaving a squash court while on sick leave.
But he claimed he was exercising to aid his return to work.
'Conscious of inconvenience'
On Tuesday the RMT said the action had been called off after the intervention of the conciliation service Acas.
Bob Crow, general secretary of the RMT, said: "We will continue to seek a fair hearing for the RMT member who has lost his job through an unfair and discredited disciplinary decision.
He added: "The union and our members are, of course, happy that it has been possible to avoid industrial action over the Christmas period.
"It was action which we were not undertaking lightly, conscious of the inconvenience which it would create for the travelling public."
LU said it was "very pleased" the festive season would
now be disruption-free.