Boston Blue will see the return of several Blue Bloods characters, but one will have a different face.
Mika Amonsen takes over the role of Danny Reagan’s (Donnie Wahlberg) youngest son, Sean Reagan, on the new CBS series Boston Blue, which premieres on Friday, October 17. Andrew Terraciano previously portrayed the character on all 14 seasons of Blue Bloods, which ran on CBS from 2010 to 2024.
Boston Blue will pick up with Sean now living in the titular Massachusetts city, continuing his family’s legacy by becoming a Boston PD patrolman. While Sean left New York City to forge his own path, his work and family lives become intertwined when Danny moves to Boston and joins the force as the partner of Detective Lena Silver (Sonequa Martin-Green).
The series also stars Maggie Lawson, Gloria Reuben, Ernie Hudson, and Marcus Scribner. Blue Bloods alum Bridget Moynahan will also return as Danny’s sister, Erin Reagan.
Scroll down to get to know Amonsen ahead of his Boston Blue debut.
Where is Mika Amonsen from?
According to his CBS bio, Amonsen was raised “just outside Toronto and continues to reside there today.” Amonsen’s hometown also happened to be the show’s filming location, as he and Wahlberg were spotted filming in Toronto in July at a location dressed to look like Boston’s Fenway Park.
Seacia Pavao/CBS ©2025 CBS Broadcasting, Inc. All Rights Reserved
When did Mika Amonsen start acting?
The Canada native got his professional acting start in the late 2010s with roles in films and shows such as Designated Survivor, Christmas Encore, Suits, Good Witch, Midway, and Hudson & Rex.
In recent years, Amonsen has continued to book roles on shows like The Republic of Sarah, Murdoch Mysteries, EZRA, and Pachinko. He also appeared in the horror movies Thanksgiving and Whistle in 2023 and 2025, respectively.
What does Mika Amonsen do outside of acting?
Amonsen has a talent for music, as his CBS bio states that he “found early creative success as the lead guitarist of a Toronto-area rock band.” Before he transitioned to acting, Amonsen’s band produced a 10-track album, performed across local venues, and opened for Canadian legend Kim Mitchell,” the bio reads.
Is Mika Amonsen dating anyone?
Amonsen does not appear to be on social media, so his current relationship status is unknown.
What has Mika Amonsen said about joining the Blue Bloods TV universe?
“It’s kind of surreal that I was watching Andrew grow up on screen back then, and now I’m stepping into that same world,” Amonsen exclusively told TV Insider of taking over for Terraciano as Sean. “I went back to his later episodes to study his dynamic with Danny and his humor. And I’ve tried to carry over that warmth, his dad’s stubborn streak, and a quiet intelligence that really feels like a Reagan.”
He also shared praise for his onscreen father. “Donnie is incredible! He’s full of energy, cracking jokes, and the second the cameras roll, he’s laser-focused,” Amonsen stated. “He’s also been so generous, both as a scene partner and by giving me advice on stepping into long-running franchises. He makes you feel like family from day one.”
Wahlberg, for his part, also had nothing but kind words to say for his costar. “Mika is phenomenal,” he told TV Insider. “It is usually an arduous process recasting a role, but we found a very special actor who the audience is going to fall in love with.”
Boston Blue, Series Premiere, Friday, October 17, 10/9c, CBS