The band have been added to Sunday's schedule, along with electronic house duo Simian Mobile Disco.
Underworld, who were recently confirmed to headline this August's SW4 festival, will also make an appearance on Saturday.
The acts join a bill which already includes Saint Etienne, Lethal Bizzle and Villagers.
Tickets are available now for this year's Camden Crawl, which takes place in London between April 30 and May 1.
> British Sea Power: "We are a rock band"