Ad2One, which has managed UKTV's online sales since 2003, will relinquish the account in January 2009.
UKTV, which is owned by Virgin Media and BBC Worldwide, last month rebranded UKTV Drama as Alibi and launched entertainment channel Watch, which took over the channel slot previously filled by UKTV Gold+1.
It has also embarked on a strategy to significantly boost the volume of video content carried across its various sites -- giving viewers the chance to view additional programme content online.
Amber Coley, UKTV's head of online advertising, who will manage the relationship with IDS, said that UKTV is investing heavily in online as part of an overarching network rebrand "to drive both traffic and revenue to our websites".
Included on the site is short-form content for shows 'Argumental' and 'Batteries Not Included'.
As a result of UKTV's investment in online, the broadcaster said that unique users across its 10 websites are up 26% month on month to 1.5m and that page impressions have increased 20% to 10.6m.
The company is predicting that the number of unique users and page impressions will double once the sites are fully operational.
Coley said: "With five new sites launched in the last two months and video streaming a key development area for us, IDS are the best placed team to maximise our commercial opportunity."
Julia Jordan, UKTV's executive director of business and operations, said: "Ad2One have done a fantastic job representing UKTV, but strategically it makes sense for IDS to sell our websites alongside our channel brands to offer a truly cross-platform sell for the first time."
UKTV is also planning to relaunch UKTV People as Blighty and UKTV Documentary as Eden early next year.