Paul Evans, ABI chairman, said the document would address the concern that vulnerable people might renew their policy without checking they are getting the cover they need "at a fair price".
The code comes into effect this month, from which point insurers and brokers will have 12 months to prepare for its commitments. The trade bodies will produce a report in one year to assess its impact.
The industry already has its own system in place to help vulnerable policyholders, but Lord Hunt, chairman at BIBA, said the code would raise awareness where customers could get additional support and advice when needed. He also believed the code would "boost trust in the insurance sector".
The document does not define vulnerability and individual firms are to determine the term depending on their customer base.
However, it does point to a range of factors that may lead to vulnerability in financial services, including a physical disability, severe or long-term illness, mental health issues and people with low literacy, numeracy or financial capability skills.
Under the code participating insurers and brokers should ensure staff are adequately trained to recognise vulnerable policyholders and be able to offer flexible options to help address needs where necessary.
They will ensure that options and how to exercise them are clearly set out and to periodically review policies to ensure customers are aware if any more suitable alternative products now available.
The industry will also ask these customers at renewal if their current policy and terms meet their needs, and make clear the importance of reviewing their cover.
Insurers and brokers will also consider additional methods of communications such as a telephone call to help policyholders through the renewal process.
Evans said: "I am delighted to see the strong spirit of partnership with which we are working with BIBA to build the reputation of the industry and the trust of our customers."