Union leaders at food manufacturer Bakkavor say the increases were secured after a dispute over management plans to introduce a £250 sign-on bonus for new staff.
The union Unite says it took action after a request for a similar incentive payment to the existing workforce was refused.
But Bakkavor bosses say the pay increase had been decided some time ago and was over and above its normal pay award.
Officials for Unite say that its intention to move towards industrial action helped secure permanent pay increases of between one and eight per cent, depending on roles and previous pay rates, for workers at four sites.
The sites are Bakkavor Salad in Bourne, Bakkavor Pizza in Holbeach, Bakkavor Meals in Sutton Bridge and Bakkavor Desserts in Newark.
The pay agreement meant the £250 starter rate payment was withdrawn.
As staff at Bakkavor Foods in West March Road, Spalding, already received a higher rate of pay than the other factories, Unite negotiated a £100 one off payment to all hourly paid workers.
Unite regional officer Neelam Verma said: “Credit must go to our members at Bakkavor, who made it entirely clear that they were not going to accept the introduction of unfair starter rates, which failed to value the existing workforce.
“Once Bakkavor realised the level of anger on the shop floor, it returned to the negotiating table and agreed the improved pay rates.
“Unite will continue to work with its members to ensure that pay rates are further increased in the future.”
Unite general secretary Sharon Graham said: “This is a highly important deal for Unite’s members at Bakkavor who, by standing together, have secured permanent pay rises for all workers.
“Unite is absolutely committed to defend the jobs, pay and conditions of all its members and this result for workers at Bakkavor, many of whom are low paid, demonstrates our commitment in action.”
A spokesman for Bakkavor said: “Bakkavor, the UK’s leading fresh prepared food manufacturer, is set to implement a discretionary, out-of-cycle pay increase for the majority of its factory-based colleagues around the UK, which is over and above its normal annual pay award.
“The pay increase has been planned by Bakkavor for some time, after competitive benchmarking of rates of pay locally at each of its manufacturing sites.
He added: “The move, has been well received by Bakkavor colleagues, who have played a huge part in helping to maintain food supply throughout the pandemic and during more recent supply chain challenges.”