Staff also maintained all existing terms and conditions that had been under threat – including sick pay, monitoring workers’ toilet breaks and changes to bank holiday working practices, Unite said.
Further assurances over redundancies and retraining have also been guaranteed as part of the deal.
Unite general secretary Sharon Graham said: “We backed our members at Jiffy in their fight for better pay and to protect their terms and conditions, and because they fought hard for what was rightfully theirs, they won the dispute.
“They should be applauded for standing firm against this household name who tried so hard to short change them.”
The union previously said the company, which is synonymous with padded envelopes and other packaging materials, made nearly £6m in gross profits according to their last accounts “so can easily afford to make a decent pay offer to their employees”.
