Bobby Thomas headed an equaliser in the 84th minute to cancel out Ryoya Morishita's opener and give the Sky Blues the point they needed to confirm a top-two finish, sending more than 7,000 travelling supporters into celebration at Ewood Park.
Manager Frank Lampard, speaking to Sky Sports, called the achievement a landmark moment in his career. "To go and get promotion automatically as a non-parachute team with three games to go... these boys have managed to achieve something special and unique," he said.
"This is what it's about. Coming here and getting a point at this stage isn't easy. Doing this after 25 years... wow."
"The resilience to come back after losing in the play-offs last season. We spoke in the summer about what we could do this season and whether we could finish third or fourth to get a home play-off. It's such a good feeling that the boys have managed to get it over the line."
Lampard, 47, took charge at the CBS Arena in November 2024 with the club 17th in the Championship. He guided them to the play-off semi-finals in his first season before losing to Sunderland, and has led them to the top of the table throughout this campaign. He also paid tribute to predecessor Mark Robins, who led the Sky Blues to two promotions and a play-off final.
"I'm proud of myself and the staff. We've fallen in love and this is right up there with what I have achieved. I'm very proud to be the manager."
Owner Doug King, who took sole control of the club in January 2023, said the moment felt "surreal." He acknowledged that dismissing the popular Robins had been an unpopular call but said it had been "a change of direction" the club needed.
"Twenty-five years is a huge amount of time. Getting out of this league is very difficult and we did it. We got the whole city together."
Coventry can still win the Championship title, with second-placed Ipswich Town 13 points behind with five games remaining.