The grandson of Irish immigrants, Boyle was born in Chicago. His parents soon moved to Rhode Island, where he graduated from high school in Warwick. He attended Colby College in Maine, majoring in literature, and began to write short stories and poetry.
Boyle's first career was in journalism. He began as a reporter at the Rumford Falls Times, a weekly in Rumford, a Maine paper-mill town, then moved to the Morning Sentinel, a daily in Waterville, Maine, his old college town, going on to become a full-time columnist on the paper.
As Boyle traveled around Maine looking for stories, he invented a freelance journalist-detective called Jack McMorrow. The first McMorrow mystery, Deadline, was published in 1993. Two years later, it was followed by Bloodline, and there are now nine books in the series.
Boyle left the Morning Sentinel in 1999 but until 2001 continued to write a column for the paper from time to time. In 2000, he became editor of Colby Magazine.