Jordan Ayew’s angled effort just past the hour put the Villans on course for victory, but super-sub Winnall climbed highest to turn home Cole Kpekawa’s flick.
Conor Hourihane’s angled free kick drew a smart save from Pierluigi Gollini while Jonathan Kodjia and Ayew forced good saves out of Adam Davies in a cagey first half.
Ayew’s effort appeared good enough to have won it for Villa with Adam Hammill’s low effort the best the Reds could muster, until Winnall popped up to snatch a point.
After a quiet opening, a loose ball in the Villa penalty area span the way of Tom Bradshaw but the striker was denied by a last-ditch block.
Conor Hourihane’s corner was headed just over by the towering Marc Roberts and Villa responded with their first two efforts on goal.
Mile Jedinak’s close range header was easily caught by Adam Davies and he was called into action again moments later to repel Jonathan Kodjia’s fierce drive.
After Hourihane won the ball on the edge of the area, he slipped in Tom Bradshaw but he was unable to find the target from just inside the area.
Hourihane did find his range on 23 minutes, whipping a free kick at Pierluigi Gollini’s near post and drawing a smart save from the Italian.
Cole Kpekawa was the first name in the book just after the half hour for a strong challenge on Jack Grealish and Sam Morsy was cautioned shortly after for stopping Albert Adomah in full flight.
Kpekawa tried to unleash a 30-yard piledriver but saw his effort fly over the top of the crossbar as the Reds finished the half the stronger, passing the ball around with real purpose.
The Villans began the second half the brighter, fashioning an opening on 50 minutes when Kodjia poked Aaron Tshibola’s low centre on target, only for Davies to spread himself and turn the ball away.
Josh Scowen’s surging run was brought to an abrupt holt when Leandro Bacuna upended him in full flight, resulting in a yellow card for the full-back.
The visitors drew first blood just past the hour when Ayew picked up the ball from a tight angle, cut inside Andy Yiadom and fired low into the bottom corner.
Mile Jedinak, Angus MacDonald and Aaron Tshibola all went into the book for strong challenges soon after while Adomah did well to turn Hourihane’s inviting centre to safety.
Adam Armstrong, Sam Winnall and Adam Hammill were all sent on by Paul Heckingbottom in a bid to level the scores, with the latter firing just wide of the upright, after Kodjia had drawn another good save from Davies.
Villa continued to pepper the Reds goal but they held firm and got their reward in the final minute of normal time.
The visitors failed to clear their lines from a corner and Kpekawa’s looping header was met by a towering leap from the number nine, to send Oakwell wild.
Kodjia almost snatched it in stoppage time for the visitors, but Davies again got down smartly to ensure a point for the Reds.
Reds: Davies (GK), Yiadom, Roberts, MacDonald, Kpekawa, Scowen, Hourihane (C), Morsy (Armstrong, 66’ ), Kent, Bradshaw (Winnall, 66’ ), Watkins (Hammill, 72’ ).
Subs: Townsend (GK), A. Jackson, Bree, Lee.
Aston Villa: Gollini (GK), Bacuna, Elphick, Chester, Cissokho, Grealish Tshibola (Westwood, 75’ ), Jedinak, Adomah (Gestede, 86’ ), Kodjia, Ayew.
Subs: Bunn (GK), Baker, Hutton, Amavi, McCormack.