Who is Andrew Terraciano? Everything to know as the Blue Bloods alum joins the cast of Boston Blue

Andrew Terraciano is well known for playing Sean Reagan, Detective Danny Reagan's youngest son (Donnie Wahlberg), on the hit CBS show Blue Bloods for a long time. He played the character for all 14 seasons of the show, which ran from 2010 to 2024. In a way, he grew up on screen.

But in the next part of the Reagan family story, the spin-off Boston Blue, Sean's character changes. The role has been recast, even though the character moved to Boston to become a police officer. The new show, which comes on Fridays at 10/9c, has Mika Amonsen playing Sean Reagan.

This recasting decision is a big change for the actor and the fandom, but it is part of a new creative direction for the character as he joins the police force. Terraciano recently talked about the change and had a nice and mature attitude about his time on the show and the role change.

As stated by Terraciano on December 7, 2025, to Deadline,

"It’s beautiful because you’ll always remember every single line and every day that you had the opportunity to be that character. It doesn’t mean for even a second that somebody else can’t go and do something beautiful with it.”

Further, said Terraciano added, “I got the joy of playing Sean, and I got to send him off into the world. Now somebody else gets that joy. We’re both getting to show what we do and then send Sean off into the world.”

Andrew Terraciano: The Blue Bloods Alum Joins the Cast of Boston Blue

Andrew Terraciano is an American actor who is most famous for playing Sean Reagan, the youngest son of NYPD Detective Danny Reagan (Donnie Wahlberg), on the CBS crime drama Blue Bloods from 2010 to 2024. This long run on a popular show is his first and only big acting job so far, with almost 300 episodes. His older brother, Tony Terraciano, was also in the show as Jack Reagan, his on-screen brother.

In an interview with US Weekly on December 5, 2025, he mentioned the excitement he had after knowing about this role,

“I had somebody call me — actually the day that I was graduating — and they had spoken to my mom and she called me [crying]. They were like, ‘They might be looking for a different Sean.’ Shortly after we got the news, Donnie called me. It was a really beautiful moment of getting to hear from an old friend but also somebody that you respect so much and have learned so much from.”

Recasting of Boston Blue

Fans were quite surprised when they heard that someone else would play Sean Reagan in the spinoff Boston Blue. Sean moves to Boston to follow in his family's footsteps in law enforcement and joins the police force as a rookie cop. The producers, however, opted for a new actor, Mika Amonsen, to play the role, a decision they noted was due to a "new creative direction for the character" and the desire for a "slightly different version of Sean" with a "new energy."

Co-creator Brandon Margolis explained the reasoning, stating,

"We wanted a character that feels familiar, an actor that does resemble the character that we watched grow up. But as you saw in the pilot, he has made some life changes and having joined the police force, he is really picking up that family mantle." He added that this change creates "new storytelling lanes to explore," such as exploring Danny Reagan as a father to an active cop.

Andrew Terraciano revealed how he learned about the recasting, recalling that his mother received a call about the potential change on the day of his graduation. This was followed shortly by a call from his former on-screen father, Donnie Wahlberg. 

Boston Blue episodes stream on CBS.