The company also announced changes to shift patterns at its distribution centres, moving from five-day eight-hour shifts to four-day 10-hour shifts.
The move will give workers three days off every week.
Amazon's temporary workers will be offered the chance to take up the 800 new permanent posts on guaranteed hours as opposed to zero-hours contracts.
Catherine McDermott, UK operations director at Amazon, said: "Every one of our employees will be working over the Christmas period to delight customers by delivering millions of items on a daily basis and we are pleased to be creating 800 new permanent roles in our centres ahead of the Christmas period.
"Having recently reviewed and improved pay rates and overall compensation package, we are now moving to a four-day week which will provide employees with more days of free time and the potential for savings in terms of time and money."
Amazon has more than 4,500 permanent employees in its UK fulfilment centres and recently announced that it would be hiring in excess of 15,000 people on a temporary basis for the Christmas period.