The sponsorship kicks off with Channel 4's Relocation Relocation on January 7 and includes home-related programming including: Grand Designs; Property Ladder; Location, Location, Location; and Selling Houses.
It is expected to include new property programmes such as The Chain, which documents the trials of moving house.
The programmes will air throughout the year on Tuesday and Wednesday evenings between 8pm and 9pm.
The deal includes sponsorship of the 4Homes web site and will be supported by an extensive consumer promotions campaign.
Direct Line is best known for motor insurance but, says group marketing director Jim Wallace, the 4Homes sponsorship will be used to promote the company's home-related products, including insurance, mortgages and Home Response 24, its new 24-hour home emergency service for heating, electrical and plumbing emergencies.
Idents by 4Creative, Channel 4's in-house creative agency, will feature Direct Line's trademark red phone next to a house in which each of the rooms represents a different product in the Direct Line portfolio. The red phone is portrayed as a means of resolving house-related problems, such as burglary.
Wallace added that the 4Homes sponsorship is a good fit with Direct Line customers who tend to be young and upmarket.
Before linking with Channel 4, Direct Line sponsored ITV's Better Homes for two years.
4Homes was previously sponsored by Npower, which chose not to renew the deal for 2004. The 4Homes sponsorship was negotiated on behalf of Direct Line by Chris Holdom at SponsorCom, the sponsorship arm of MediaCom, and by Rob Ramsey on behalf of Channel 4.
Direct Line is owned by Royal Bank of Scotland; it has been retained as the consumer-facing brand.