2000–2026: Valli-led tours and Jersey Boys
By the early 2000s, the Four Seasons tours were falling in attendance and revenue, prompting Valli to seriously consider retirement. He instead assembled a new backing quartet consisting of Landon Beard, Todd Fournier, and brothers Brian Brigham and Brandon Brigham. The success of the musical Jersey Boys largely saved the Four Seasons.
A 3CD + 1DVD box set ...Jersey Beat... The Music of Frankie Valli & the 4 Seasons was released in mid-2007, marketed as the most comprehensive collection of Four Seasons music yet. The album title Jersey Beat is a play on Jersey Boys, a successful Broadway musical about the Four Seasons, as well as on Mersey Beat, a term first coined as the title of a music magazine published in Liverpool, England, from 1961, but subsequently also used to describe Liverpool's "beat music" culture of the early 1960s.
In 2008, the Four Seasons' "Beggin'" was revived by two acts. Pilooski made an electro remix of that song, while rap act Madcon used it as the basis of their song "Beggin'". The latter reached No. 5 in the UK charts and was a hit across Europe. The song was featured in a TV commercial for adidas shoes entitled "Celebrate Originality". The Adidas commercial is a popular hit on YouTube and features a house party with famous celebrities such as David Beckham, Russel Simmons, Kevin Garnett, Missy Elliott, Katy Perry, and Mark Gonzales. Also in 2008, Gaudio and Robinson recorded Jersey Babys: The Instrumental Music of Frankie Valli and the Four Seasons for Kids, an instrumental children's album, under the Four Seasons brand but without Valli's direct involvement. Jersey Babys [sic] was originally envisioned by Danielle Lahlezar, Gaudio's daughter from his first marriage to Brit Olsen (to whom the album was dedicated). Jersey Babys was re-released in 2024 with an additional bonus track.
Members of the 1970s lineup of the group (Polci, Ciccone, and Shapiro) reunited without Valli in 2011 as the Hit Men; it toured with several other session musicians of good repute. Shapiro has continued the Hit Men as a standalone project after Ciccone died in 2016 and Polci withdrew from the group in 2017. Long and Polci both have had stints with the Jersey Four, a Four Seasons tribute act based in New Jersey.
In 2015, former longtime guitarist Larry Lingle rejoined the band, and he left for the second time after a concert on May 1, 2016. On September 10, 2016, the band performed with the BBC Concert Orchestra in Hyde Park, as part of the BBC Proms in the Park.
In 2018, the Beard/Fournier/Brigham quartet spun off and began performing as the Modern Gentlemen, with Valli's blessing, and Valli recruited a new quartet of singers to back him. Beard, Fournier, and the Brigham brothers performed as the Four Seasons for 15 years, longer than any other lineup and longer than any of the band's other members except Valli, Gaudio and Robinson.
In 2020, the group launched a YouTube channel. During that same year, and continuing into 2021, during earlier phases of the coronavirus (COVID-19) pandemic, the group virtually re-recorded three of their songs ("Harmony, Perfect Harmony", "Let's Hang On" and "Silence Is Golden"), as well as Valli's hit, "Grease", for their YouTube channel. The channel has since added archival videos from the group's television appearances and records by Four Seasons tribute acts, such as former Jersey Boys cast members.
A limited-edition 44-disc career box set called Working Our Way Back to You: The Ultimate Collection was initially going to be released in the summer of 2021 by The Four Seasons Partnership and Snapper Records, but it missed the release due to the COVID-19 pandemic. However, the box set was later rescheduled for release on December 9, 2022, before the release date was pushed back to April 14, 2023. The box set was eventually released on June 2, 2023, by The Four Seasons Partnership and Madfish/Snapper Music. It includes every album released by the band (including both mono and stereo mixes, where available), a CD of unreleased tracks from the band's Mowest years, three live shows taken from soundboard recordings as well as numerous other rare tracks and alternative versions.
The Four Seasons announced their farewell tour, The Last Encores Tour, to run through 2024, including several extended stays at the Westgate Las Vegas Resort & Casino. In an interview with the Los Angeles Times, Valli did not rule out future appearances after the tour, stating that "I'm not sure whether I'm gonna keep going out." The tour was eventually extended into 2025, with representatives for Valli responding to criticism of him touring at such an advanced age and fears of elder abuse by assuring that Valli was "doing just fine and super happy to be still performing." In a statement to People, Valli indicated a willingness to continue performing as long as audiences continued to buy tickets, responding to accusations of lip syncing by noting that his touring production was using a strategy it had long relied on for studio recordings "layering vocals and instruments" to allow the Seasons to maintain a sound similar to that heard in the 1960s despite Valli's age. The tour was abruptly halted on September 29, 2025, due to Valli suffering an illness, and most remaining tour dates were cancelled. Valli made a brief attempt at resuming touring in February 2026, an attempt that was cut short after only three concerts; after these three shows, Valli announced that the shows scheduled in April and May 2026 would be his last in those cities. The April and May shows were ultimately never played, as Valli again announced the cancellation of his remaining tour dates on May 29, 2026 through the end of the year at minimum; he stopped short of fully retiring, stating that he would reassess his health in 2027, but that his promoters had been instructed to refund any tickets sold and not reschedule the cancelled dates. Valli's brother, singer Bobby Valli, indicated in August 2026—shortly after Valli had made his first public appearance since his most recent concerts, looking visibly frail and weak—that Frankie "will now retire(.)" Valli's publicist released a statement stating that this was not the case. There has been no indication from representatives of Gaudio or Valli of what will happen to the Four Seasons brand once Valli is no longer able to lead it.
Throughout the Four Seasons' 66-year existence, no incarnation of the group has ever won a competitive Grammy Award. In 2025, Valli was awarded the Grammy Lifetime Achievement Award, the only Grammy the group has yet received.