The decision was confirmed by UFC President Dana White in the aftermath of a Fight Night event in Azerbaijan, ending seven months of limbo at the top of the division.
Aspinall, 32, had held interim status since a blistering knockout of Sergei Pavlovich in November 2023, and now becomes just the third Briton in UFC history to claim full championship honours after compatriots Michael Bisping and Leon Edwards.
"Jon Jones called us last night and retired," White stated bluntly.
"Tom Aspinall is the heavyweight champion of the UFC."
Jones, 37, widely regarded as one of the most dominant and controversial fighters in MMA history, ends a career that began in 2008 and reached legendary status in both light‑heavy and heavyweight divisions.
The youngest-ever UFC champion at 23, he defended 12 titles and defeated icons such as Mauricio 'Shogun' Rua, Daniel Cormier and Stipe Miocic.
His ascent to heavyweight gold began in March 2023, culminating in a dominant performance over Miocic at UFC 309 in November 2024.
Yet despite Aspinall's rise and relentless calls for a unification bout, Jones repeatedly swerved the matchup, claiming that a fight against the Englishman would do little to enhance his legacy.
The irony, of course, is that legacy now includes the avoidance of what could have been a defining contest. For Aspinall, who White described as "incredible through this whole process", the recognition has been hard earned.
"I obviously feel bad for Tom that he lost all that time and obviously money, but we'll make it up to him," White added.
"Tom Aspinall's a good guy. He's been incredible through this whole process.
"He's been willing to do anything, fight him anywhere at any time and do this, and now he's like 'I'll fight anybody - you tell me who and I'll fight them'."
Aspinall has spent 19 months in championship limbo and just three minutes and 22 seconds inside the Octagon since the start of 2023, a staggering statistic that underlines both his inactivity and his efficiency in finishing fights.
The Salford native has remained vocal and game throughout, declaring after the announcement: "For you fans, it's time to get this heavyweight division going. An active undisputed champion."
That activity is expected to resume this summer or early autumn, with French contender Ciryl Gane the most likely first challenger.