As part of the five-figure deal, SwapitShop will unveil a branded 'auction frenzy' on its site this week, offering PartyMoto merchandise such as T-shirts, stickers, antenna rings and dangling characters for mobiles.
Consumers can use SwapitShop's Swapits online currency to bid for items, which are limited to three weeks of bidding.
To promote the auction, Swap-itShop has created online ads and email newsletters, which it will send to 200,000 users.
Competitions will also drive traffic to PartyMoto.com, where users can take part in games and personality tests, and Party-Moto branding will appear on swap packages sent to SwapitShop users. Low reserve prices of one Swapit on some items will encourage users to join in.
Jonathan Attwood, chief executive of SwapitShop's parent company, Webswappers, said: "Motorola is looking to create a whole lifestyle around mobiles, and the PartyMoto site is aiming at kids and teens, which is a good fit for us. Interactive campaigns and sponsorship packages really capture the imagination of our audience."