The hosts had lost half of their games at Oakwell prior to today's encounter, but managed to extend their mini unbeaten run to four games by taking a surprise point from Nuno Espirito Santo's side.
Cardiff City had temporarily moved to second in the table earlier in the day with a 4-0 thumping of Sunderland, while Bristol City suffered their third consecutive defeat thanks to a late goal from Norwich City's James Maddison.
A penalty in the fifth minute of time added on saw Fulham claim a dramatic late win at Middlesbrough, while a long-range strike from Bersant Celina saw Ipswich Town past promotion-chasing Leeds United.
Brentford moved to three points off the playoffs with a 2-0 win over relegation-threatened Bolton Wanderers at Griffin Park, and Queens Park Rangers secured more daylight from the dropzone with a 3-1 triumph at Burton Albion, who stay put in 22nd place.
Results in full: Cardiff City 4-0 Sunderland, Barnsley 0-0 Wolverhampton Wanderers, Birmingham City 0-3 Derby County, Brentford 2-0 Bolton Wanderers, Bristol City 0-1 Norwich City, Burton Albion 1-3 Queens Park Rangers, Hull City 0-0 Reading, Ipswich Town 1-0 Leeds United, Middlesbrough 0-1 Fulham, Millwall 1-1 Preston North End