This was the first WrestleMania held after WWE merged with the Endeavor subsidiary Ultimate Fighting Championship (UFC) in September 2023, under the banner of TKO Group Holdings.

It is the longest-running professional wrestling event in history and is held annually between mid-March to mid-April, featuring wrestlers from WWE's Raw and SmackDown brand divisions.

[15] Hours before WrestleMania 39 Night 2 began, CNBC reported via multiple sources that a deal between WWE and Endeavor, the parent company of Ultimate Fighting Championship (UFC) via Zuffa, was imminent.

Additionally, it was available to livestream on Peacock in the United States, Disney+ Hotstar in Indonesia, Disney+ in the Philippines, Binge in Australia, Abema in Japan, SonyLIV in India, Shahid and SSC in the Middle East and North Africa, and the WWE Network in all other countries.

Rapper and YouTuber IShowSpeed accompanied Logan Paul to the ring for his WWE United States Championship defense (wearing a Prime bottle costume at the start and then revealing himself while the match was in progress).

[42] This decision drew intense fan backlash with the hashtag #WeWantCody trending on social media worldwide, which caused WWE to legitimately pivot their story plans.

However, Rhodes appeared and asserted that since he won the Royal Rumble, he earned the right to decide the main event and announced that he had reversed his decision and would challenge Reigns for the title at WrestleMania.

[50] At SummerSlam in July 2022, Bayley made her return from injury alongside Dakota Kai and Iyo Sky with the trio dubbing themselves Damage CTRL.

Jade Cargill, who was making her debut as an official roster member of the brand that night, made the save after weeks of teasing a feud with the faction.

Later, it was announced that Cargill, Naomi, and Belair would face Damage CTRL (Kai, Asuka, and Sane) in a six-woman tag team match at WrestleMania XL Night 1.

[57] On the March 25 episode of Raw, it was announced that CM Punk, who had issues with both Rollins and McIntyre but had gotten legitimately injured at the Royal Rumble, would serve as a special guest commentator for the World Heavyweight Championship match.

[54] On the March 11 episode of Raw, Raw General Manager Adam Pearce and SmackDown General Manager Nick Aldis announced that at WrestleMania XL, The Judgment Day (Finn Bálor and Damian Priest) would defend the Undisputed WWE Tag Team Championship in a Six-Pack Tag Team Ladder match.

[63] Styles later explained that he attacked Knight for taking his spot in a tag team match at Fastlane in October 2023, saying he "stepped over his dead body" to get ahead.

[50] The following week, SmackDown General Manager Nick Aldis announced that Paul would defend the United States Championship against Owens and Orton in a triple threat match at WrestleMania XL,[65] which was later confirmed for Night 2.

[72] On the following episode of SmackDown, fellow LWO member Carlito accused Escobar of intentionally leaving the brass knuckles on the ring apron.

[49] Three weeks later, Escobar defeated Rey after interference from the latter's son, "Dirty" Dominik Mysterio, who had turned on his father at Clash at the Castle in September 2022 to join The Judgment Day.

Andrade, who assisted Rey in fending off Escobar and Dominik earlier that night and reunited with LWO's Zelina Vega, was named Lee's replacement.

[25] At SmackDown: New Year's Revolution on January 5, Karrion Kross, accompanied by Scarlett, attacked The Pride (Bobby Lashley, Angelo Dawkins, and Montez Ford) with help from the returning Authors of Pain (Akam and Rezar), accompanied by Paul Ellering, with Kross, Scarlett, Authors of Pain, and Ellering forming a faction called The Final Testament.

[55] On April 1, a six-man tag team Philadelphia Street Fight pitting The Final Testament against The Pride was confirmed for WrestleMania XL Night 2.

[54] Brock Lesnar, who last appeared at SummerSlam in August 2023, was planned to return at the Royal Rumble and be featured in a match at WrestleMania XL, reportedly against Gunther for the Intercontinental Championship.

[75] CM Punk, who after nearly 10 years made his return to WWE at Survivor Series: WarGames in November 2023, legitimately tore his right triceps during the men's Royal Rumble match.

[77] Next, The Judgment Day (Finn Bálor and Damian Priest) defended the Undisputed WWE Tag Team Championship in a Six-Pack Tag Team Ladder match against #DIY (Johnny Gargano and Tommaso Ciampa), The New Day (Kofi Kingston and Xavier Woods), The Awesome Truth (The Miz and R-Truth), A-Town Down Under (Austin Theory and Grayson Waller), and New Catch Republic (Pete Dunne and Tyler Bate) in which both sets of titles had to be retrieved for the match to end.

[77] Next, Jade Cargill, Bianca Belair, and Naomi faced off against Damage CTRL (Dakota Kai, Asuka, and Kairi Sane) in a six-woman tag team match.

[78] In the first match, Seth "Freakin" Rollins defended the World Heavyweight Championship against Drew McIntyre, with CM Punk as a special guest commentator.

[78] After the match, McIntyre let his wife hold the title, then walked over to the announce table to mock Punk, telling him not to come back, or he would end his career.

[78] In the next match, Logan Paul (accompanied by the Prime energy drink mascot) defended the United States Championship against Randy Orton and Kevin Owens.

[78] In the main event of Night 2, Roman Reigns (accompanied by Paul Heyman) defended the Undisputed WWE Universal Championship in a Bloodline Rules match against Cody Rhodes.

[92][93] The next week, he defeated Kofi Kingston in a quarterfinal bout, then defeated Jey Uso in the semifinals on 20 May,[94] and finally Randy Orton in the finals at the King and Queen of the Ring event, albeit controversially, after Orton had a shoulder up during the match's ending crucifix pinfall, to win the tournament, earning a World Heavyweight Championship match at that year's SummerSlam event.

[97] At the event on 3 August, Gunther defeated Priest to win the World Heavyweight Championship for the first time in his career, notably after interference from Judgment Day member Finn Balor.

[111] In the main event of the August 2 episode of SmackDown, the night before SummerSlam, Fatu and Tama Tonga defeated DIY (Johnny Gargano and Tommaso Ciampa) to win the WWE Tag Team Championship.