The announcement was made shortly after the California State Athletic Commission (CSAC) officially changed the result of Jones' third-round TKO victory over Cormier on July 29 to a no-contest.
In an appearance on UFC Tonight, Cormier (19-1) suggested he didn't want the title back at first, but ultimately was going to fight for the belt either way and accepted reinstatement for financial reasons.
"I talked to [CSAC] and was like, 'I lost. I lost the fight,'" Cormier said. "As a competitor, that's how I felt. [UFC president] Dana White called me today and said, 'If it's a no-contest, then the fight didn't happen.'
"Now, people will say stuff like, 'You got handed the belt.' He cheated. The reality is, for me to say, 'I don't want this title,' when I was going to be [fighting] in a championship anyway, financially it's just a big difference if I don't fight as the champion as opposed to fighting for a vacant title."
Jones (22-1) tested positive for metabolites of Turinabol, an anabolic steroid. He has denied knowingly taking any banned substances.
CSAC waited to change the result of the July 29 title fight until results of Jones' "B" sample confirmed the failed drug test. The commission received those results Tuesday.
This is the second failed drug test of Jones' career. He served a one-year suspension after testing positive for two anti-estrogenic substances in July 2016. Jones stated those substances were the result of a contaminated sexual enhancement pill.
Widely considered the greatest fighter of all time, Jones is facing a maximum four-year suspension from the United States Anti-Doping Agency (USADA) for his second failed test. He has the right to appeal any suspension.
"He has to fight this. This is a death sentence," Cormier said. "If this does what it says it can be, it's a death sentence."
The UFC has not yet announced a date for Cormier's next title defense.