The various embodiments of the present invention disclose a method and system for performing Hybrid Repeat Request (HARQ) in cellular operations over unlicensed bands. The method comprises of checking, by an eNodeB (eNB), whether an unlicensed channel is occupied by a User Equipment (UE), initiating transmission of Redundancy Versions (RVs) corresponding to a HARQ process on the unlicensed channel if the unlicensed channel is occupied by the UE, verifying if a channel occupancy period is over and an acknowledgement for the HARQ process is received from the unlicensed channel and initiating a Redundancy Version (RV) bundling for retransmission of the bundled RVs without awaiting an acknowledgment for the HARQ process from the unlicensed channel, if the channel occupancy period is not over.