Landrigan began his career at the Nashua Telegraph, where he spent 27 years as a state politics reporter.[1] He later moved to New Hampshire 1 News, and then the New Hampshire Union Leader where he serves as chief of the New Hampshire Union Leader's state house bureau.[2][3] He has also been a contributor to PolitiFact.[4]
Landrigan has been described by Politico as "an institution in New Hampshire".[2] He is the 2019 recipient of the Lifetime Achievement Award from the New Hampshire Press Association (NHPA) and his expose on allegations of sexual molestation by William Loeb III received first place in the general news category in the 2023 NHPA annual journalism awards.[5][6]