Dagenham & Redbridge compounded Forest Green's relegation fears with a trio of second-half goals at The Lawn.
The deadlock was broken when Sam Saunders' free-kick from the right was met by a powerful header from inrushing Tim Cole in the 62nd minute.
Eight minutes later the visitors made it 2-0 through Danny Foster's powerful header that easily beat Ryan Clarke.
Chris Moore put the result beyond doubt when he converted with his left foot from close range in the dying seconds.
Forest Green: Clarke, Simpson, Sall, Searle, Michael Taylor, Dove (Madjo 63), Jones, Coleman, Wanless (Gadsby 79), Abbey (Beesley 72), Meechan.
Subs Not Used: Harrison, Graham.
Dag & Red: Roberts, Blackett, Cole, Uddin, Bruce, Foster, Saunders, Southam, Griffiths (Vickers 82), Akurang (Moore 72), Mackail-Smith.
Subs Not Used: Johnson, Lettejallon, Hogan.
Goals: Cole 62, Foster 70, Moore 90.
Ref: S Bratt (West Midlands).