Palm and O2 are expected to make the announcement next week almost a month after the launch of the handset in the US.
The deal strengthens O2′s position in the smartphone market since it is already the exclusive carrier for the iPhone in the UK.
There are no details yet on Pre costings and tariffs for the UK.
News of O2′s deal with Palm was reported in The Guardian, which described the competition between O2 and Orange as "fierce".
Apple recently announced that the iPhone 3GS sold over one million units in its first weekend of its availability.
Sprint, the only wireless carrier to offer the Pre in the US, has not revealed sales numbers – although it appears to be doing reasonably well.
Estimates of its sales range from 150,000 to 300,000 units.