Bell, however, might not see another season in a Steelers uniform beyond the upcoming regular season, according to the running back's agent Adisa Bakari.
"His intention was to retire as a Steeler," Bakari said in a statement obtained by NFL Network Insider Ian Rapoport. "But now that there's no deal, the practical reality is, this now likely will be Le'Veon's last season as a Steeler."
Bell also issued a statement on Twitter:
Steelers general manager Kevin Colbert echoed Bell on the two sides working together to find a solution before Monday's deadline.
"Even though we could not reach a long-term contract agreement with Le'Veon Bell, we are excited he will be with the team in 2018," Colbert said in a statement, via the Steelers' official website. "We worked very hard to find common ground, but we were unable to accomplish that prior to today's deadline. Le'Veon will play this season under the Exclusive Franchise Tag designation.
"After the 2018 season is completed, we again will attempt to work out a long-term contract with Le'Veon in the hope that he will continue his career with the Pittsburgh Steelers."
According to Rapoport, the Steelers' final offer to Bell paid $70 million over the next five seasons ($30 million over the next two), an increase over the five-year, $60 million offer to Bell last offseason.
Regarded as one of the NFL's elite offensive weapons, Bell has topped 1,000 yards rushing in two straight seasons, a span where he also totaled 160 catches.
Bell, who ranked fifth in the NFL Network's Top 100 NFL Players of 2018, has enjoyed a prolific career as a dual-threat running back since entering the league as a second-round pick (48th overall) in 2013.
In five seasons, Bell amassed 5,336 yards and 35 touchdowns on 1,229 rushing attempts while adding 2,660 yards receiving and seven touchdowns on 312 catches.
Ultimately, though, the Steelers apparently looked beyond the individual accomplishments during the negotiations.
"It became clear the Steelers wanted to pay the position, not the player," Bell's agent told Rapoport.
Bell will make $14.5 million in 2018 under the franchise tag once he signs.