McDonald's workers will get full penalty rates and shift security from February next year in a ruling from the industrial umpire on Thursday marking the end of a tortuous three-year battle between the fast food giant and unions.

An average worker can expect about $1300 a year more, according to Retail and Fast Food Workers Union, after the Fair Work Commission tossed out the existing agreement and reverted workers to the fast food award.

Xzavier Kelly has been underpaid as much as $2000 per year compared to the minimum rates of the award. Credit:Joe Armao

But in a blow to the union and workers, the commission rejected back payments that union secretary Josh Cullinan said could have been worth as much as $300 million.

The new agreement, to come into effect on February 3, comes after 23-year-old worker Xzavier Kelly and the RFFWU brought a case arguing the existing agreement was "a hell of a lot less" pay for workers than the standard fast food award.