Incumbent agency Unity, which held the account for almost four years, chose not to re-pitch for the business.
Unity's #directfix campaign for Direct Line won the Best Integrated Campaign award at the 2016 PRWeek UK Awards.
The agency's co-founder Gerry Hopkinson told PRWeek Unity had had "tremendous fun" working with Direct Line, but said the brief "was now not a good fit for us". It is the second major client to stop working with the agency of late, after a five-year relationship with M&S came to a close last year.
Direct Line Group head of brand PR and social media Frances Browning said the insurer was "always looking to push the boundaries and was passionate about having the most diverse teams".
Browning said: "We believe moving to a multi-agency model will give us even greater creative diversity and ensure the extremely successful brand activation campaigns that have been created over the past two years will continue to evolve."
Mischief will lead PR and creative for a new campaign launching in September, while Talker Tailor Trouble Maker has been tasked with handling PR for Fleetlights, a prototype service operated by Direct Line that uses technology to bring the modern street lights to the darkest parts of the UK.
Talker Tailor Trouble Maker co-founder Steve Strickland said: "The original Fleetlights campaign that launched in November 2016 was wicked and right up our strata (see below). We're looking forward to propelling the brand forward and engaging with even more people."
The two agencies were part of the same competitive pitch process, but Direct Line Group head of news and issues Simon Henrick told PRWeek the company "was always looking to appoint two agencies".
Direct Line Group, which owns the Churchill, Privilege and Green Flag brands, works with a number of other agencies including Frank, Citigate and Van Comms.