Only the top two at the end of the regular season were guaranteed a place in English football's lucrative top flight and second-tier title-winners Wolves had already secured one of those spots heading into Sunday's final round of regular-season Championship matches.
A draw left Cardiff waiting on Fulham's result at Birmingham, but the Cottagers 3-1 loss left the London club facing the lottery of the play-offs, where the teams finishing third-sixth compete for the lone remaining promotion place.
The draw saw Cardiff return to the Premier League after a single season in the competition in 2013/14.
When Warnock took over some 18 months ago, Cardiff were at the other end of the table but Malaysian owner Vincent Tan's decision to bring the experienced manager to the Welsh capital paid dividends.
Birmingham were still facing relegation when they kicked off but first-half goals from Lukas Jutkiewicz (15) and Harlee Dean (43) settled their nerves.
Tom Cairney scored for Fulham with six minutes left but Che Adams's 89th-minute goal put the result beyond doubt.
Barnsley's 4-1 loss at Derby ended their brief stay in the Championship, with Burton -- managed by Nigel Clough -- also relegated after a 2-1 loss at Preston.
Meanwhile Bolton beat the drop in remarkable fashion after beating Nottingham Forest 3-2.
Bolton were going down with three minutes left when Forest led 2-1 after goals from Ben Osborn (70) and Jack Colback (79) overturning Adam Le Fondre's early volley.
But David Wheater (87) and Aaron Wilbraham (88) scored to keep northwest side Bolton in the division to the delight of their delirious home crowd.
Elsewhere, bottom club Sunderland stunned champions Wolves 3-0, in front of prospective new owner Stewart Donald.
On-loan pair Ovie Ejaria (19) and Ashley Fletcher (45) put the hosts 2-0 up before Paddy McNair scored Sunderland's third midway through the second half.
Atdhe Nuhiu (14, 60 and 90) hit a hat-trick in Sheffield Wednesday's 5-1 thrashing of Norwich at Hillsborough, with Wednesday's city rivals United winning 3-2 at Bristol City.
Leeds beat QPR 2-0 with goals from Kemar Roofe (30) and Kalvin Phillips (47), while Brentford and Hull drew 1-1 at Griffin Park.