The Blue Bloods Spinoff Recast: Why Danny Reagan's Son Was Replaced In 'Boston Blue'

The "Blue Bloods" universe is officially expanding, but not without a massive shake-up that has fans buzzing. As of late 2025, the confirmed spinoff, titled Boston Blue, is set to continue the story of Detective Danny Reagan, played by fan-favorite Donnie Wahlberg. This new series promises to keep the Reagan family's legacy alive, shifting the focus from the familiar streets of New York City to the gritty, historic backdrop of Beantown. The series is confirmed to premiere in 2025, bringing a fresh, new look to the established police procedural format.

However, the transition comes with a surprising and significant casting change that directly impacts Danny Reagan's immediate family. While Donnie Wahlberg reprises his iconic role, a key member of the Reagan clan has been recast for the new show, sparking intense curiosity among viewers about the reasons behind the decision and the future dynamic of the spinoff. This major casting swap is the most talked-about detail of Boston Blue as the series gears up for its debut.

Donnie Wahlberg: The Star and Executive Producer's Profile

Donnie Wahlberg is an American singer, songwriter, actor, record producer, and film producer, best known for his dual careers in music and television.

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• Full Name: Donald Edmond Wahlberg Jr.
• Date of Birth: August 17, 1969
• Place of Birth: Dorchester, Massachusetts, U.S.
• Wife: Jenny McCarthy (m. 2014)
• Children: Two sons, Xavier and Elijah, from his previous marriage.
• Music Career: Founding member of the highly successful boy band New Kids on the Block (NKOTB), which achieved massive global fame in the late 1980s and early 1990s.
• Acting Career Highlights:
  • Detective Danny Reagan in Blue Bloods (2010–2024)
  • Detective Eric Matthews in the Saw film series.
  • Caron in the war drama Band of Brothers (2001).
  • Dorsal in M. Night Shyamalan's The Sixth Sense (1999).
  • Executive Producer and Star of the new spinoff Boston Blue (2025).
• Other Ventures: Executive Producer of the documentary series Very Scary People.

The Explosive Recast: Why Sean Reagan Looks Different in 'Boston Blue'

The biggest casting news surrounding the Blue Bloods spinoff, Boston Blue, is the recasting of Danny Reagan’s youngest son, Sean Reagan. In the original series, Sean was portrayed by actor Andrew Terraciano for all 14 seasons. However, for the new Boston-set show, the role has been taken over by actor Mika Amonsen.

This decision is not a reflection of Terraciano’s performance but is likely a creative choice driven by the new series' narrative and timeline. The spinoff is expected to feature a significant time jump or a dramatic shift in Sean Reagan's storyline, requiring an actor who can portray a more mature, perhaps already-graduated, and established young adult.

Andrew Terraciano, who grew up on screen as part of the Reagan family dinner scenes, has since moved on to other projects. The role of Sean in Boston Blue, where he joins his father in Boston, is crucial to the new series' premise, which centers on Danny Reagan's life post-New York. Mika Amonsen's casting signifies a fresh start for the character, potentially exploring Sean's own career path in law enforcement or a related field in the new city.

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The storyline for Boston Blue sees Detective Danny Reagan taking a new position with the Boston Police Department, relocating to his hometown. This shift provides a natural narrative explanation for the change in his son's circumstances and appearance, allowing the showrunners to introduce a more adult Sean Reagan without breaking the long-established continuity of the Blue Bloods universe.

Everything We Know About the 'Boston Blue' Spinoff

The confirmation of the Boston Blue spinoff has been a major relief for fans following the announcement that the original Blue Bloods would conclude after its 14th season. The new procedural, which is executive produced by and stars Donnie Wahlberg, is set to premiere on CBS in 2025.

The Premise: Danny Reagan's New Chapter

The core of the spinoff is Detective Danny Reagan's return to his roots. After decades with the NYPD, Danny moves to Boston, Massachusetts—Donnie Wahlberg's real-life hometown, giving the series a personal touch. The show will follow Danny as he joins the Boston Police Department (BPD), working with a new team and tackling new challenges in a different city.

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While the setting changes from New York City, the series is expected to maintain the core themes of family, justice, and the complexities of police work that defined Blue Bloods. The title itself, Boston Blue, is a clear nod to the original show, promising a familiar yet fresh take on the police drama genre.

New and Returning Cast Members

While the show is primarily focused on Danny Reagan, the cast will feature a blend of new and potentially familiar faces, expanding the Reagan family narrative beyond the original scope.

• Donnie Wahlberg returns as Detective Danny Reagan.
• Mika Amonsen takes on the role of Sean Reagan, Danny’s son.
• Sonequa Martin-Green has been announced as a co-star, reportedly playing a key figure in the Boston Police Department who will work closely with Danny. Her addition brings a new dynamic and a fresh face to the expanding Blue Bloods universe.
• There are strong hints that other members of the Reagan police family, such as Frank Reagan (Tom Selleck), Erin Reagan, or Jamie Reagan, could make guest appearances, bridging the gap between New York and Boston. Tom Selleck himself has expressed support for the spinoff.

Donnie Wahlberg's Initial Hesitation and Commitment

Interestingly, Donnie Wahlberg initially revealed he was hesitant about committing to the spinoff series, Boston Blue. Taking on a new show immediately following the end of a long-running, successful series like Blue Bloods is a massive undertaking. However, his eventual decision to move forward highlights his commitment to the character and the opportunity to continue the story in a new, compelling environment.

The new series not only keeps Danny Reagan's story going but also gives Wahlberg a chance to film in his actual hometown, providing a unique sense of authenticity to the show. The anticipation for the Boston Blue premiere is high, as it represents the future of the beloved police drama franchise.