Hall has been working with CHI on its Carphone Warehouse account, and the partnership is now expected to extend to other CHI clients.
CHI has been seeking a direct marketing partner for the past few months.
The agency is understood to have also spoken to agencies including Rapier and Archibald Ingall Stretton.
The direct venture is expected to follow a similar format to that of its communications planning joint venture with Naked, Naked Inside, which is headed by the former Initiative planning director, Tim Allnutt.
However, while Naked Inside is a 50:50 joint venture between Naked and CHI, it is not yet known how the ownership of the direct agency will be structured.
Hall has long been seen as one of the leading figures in the direct marketing industry. He founded Barraclough Hall Woolston Gray with Chris Barraclough in 1991 and oversaw the agency's acquisition by Abbott Mead Vickers BBDO.
Following AMV's acquisition by Omnicom, Hall worked on the launch of the global Proximity network for the holding company.
He resigned from Proximity at the end of last year, saying: "I'm keeping shtum on what I plan to do next but I'm too young to retire."
Hall has kept quiet about his future plans. Some industry insiders believed he would not resurface in direct marketing, while others believed he was planning a consultancy service for clients, advising on what marketing activity would best suit their business needs.
At the launch of Naked Inside, CHI's managing partner, Johnny Hornby, said: "We want to work in a much wider arena than television, press and poster."
The launch of a direct venture will create a new revenue stream for the agency and improve its media-neutral credentials. CHI's Telegraph and Carphone Warehouse clients use Naked Inside.
Hall confirmed he had held early discussions with CHI but said that no details had been finalised.