The broadcaster's reversal of plans to enter the sector as part of the 4Digital Group will result in 15 job losses.
Channel 4 had been proposing to provide three stations: E4 Radio (music and entertainment), Channel 4 Radio (speech) and Pure4 (music).
E4 Radio was due to launch early next year, in partnership with with Bauer Digital Radio, Carphone Warehouse Group, Sky News Radio, Global Radio, UTV Radio and UBC Media Group.
‘We can no longer afford the short-term investment necessary, given that we are having to cut so deeply across all parts of the organisation,' said Duncan.
Channel 4's only remaining major new business investment is its video-on-demand service, 4oD, which is due to form part of a UK VoD joint venture with BBC Worldwide and ITV.
Industry regulator Ofcom will meet members of the 4Digital Group over the coming days.