Tykes striker Davies, a free summer signing from Chesterfield, fired home an unstoppable shot from 25 yards for his 11th goal of the season in the 79th minute to clinch a first point for Keith Hill's side in three matches.
Forest, whose fight for survival had gathered some momentum after successive league wins over Coventry and Birmingham, had taken a deserved half-time lead through Garath McCleary, who drilled home a low effort from similar distance.
Steve Cotterill's side were only denied all three points by Barnsley goalkeeper Luke Steele's brilliant sprawling save from Forest substitute Greg Cunningham in the third minute of time added on.
Teenager Paul Digby, who turned 17 last month, made his second start for Barnsley and fellow midfielder Matty Done was also recalled, while Joel Lynch and Scott Wootton returned to Forest's defence and Jonathan Greening was back in midfield.
Forest striker Dexter Blackstock made an early nuisance of himself and went close to opening the scoring in the 13th minute when heading Andy Reid's corner wide.
Barnsley's first effort on goal fell to Done, who fired a 20-yard shot wide, and when the same player crossed deep into the penalty area in the 32nd minute, defender Scott Golbourne headed over the crossbar.
But Forest took a deserved lead a minute later. McCleary pounced on a loose ball on the edge of the penalty area and drilled a low left-footed shot beyond Steele into the bottom corner.
Forest's tails were up and, after sweeping forward again, another long-range effort by McCleary was blocked by Tykes defender Stephen Foster before striker Marcus Tudgay's header came back off the post with Steele well beaten.
Barnsley went on the offensive early in the second half, with midfielder Korey Smith's shot from the edge of the area blocked by Wootton and Done's lobbed effort drifting wide of the post.
Tykes boss Hill sent on veteran striker Andy Gray for defender Jay McEveley in the 56th minute and another forward, Chris Dagnall, in place of midfielder Michael Tonge 10 minutes later as Barnsley struggled to make headway in the final third.
But the Tykes failed to carve out any clear-cut chances before Forest twice threatened to double their lead in as many minutes.
McCleary's angled shot was turned away at full stretch by Steele and Forest midfielder Adlene Guedioura's 25-yard shot fizzed over the crossbar.
Done was then the architect of Barnsley's 79th-minute equaliser. The winger made space down the left and cut the ball back to the edge of the area into the path of Davies, who crashed home a low, left-footed shot into the bottom corner.
Forest almost snatched victory in the third minute of stoppage time, but Steele thwarted substitute Cunningham with a superb save from his angled shot inside the area.