The former chairman of the Advertising Association and ad agency DDB will take over from Andrew Brown at the end of March next year but will work with him from January.
Best will chair both the broadcast and non-broadcast committees (CAP and BCAP).
The two bodies are responsible setting the codes that the Advertising Standards Authority rules on following complaints. CAP also provides advice on content for marketers and agencies.
Best has also had stints as president of the European Association of Communications Agencies and chairman of BMP DDB.
He is also a council member of the ASA and has been a council member of the IPA.
Sir Chris Powell, chairman of the Advertising Standards Board of Finance, the financing body that made the appointment, says: “James’ understanding of the advertising business and advertising self-regulation is second to none, we are lucky to have him.”