Brian Meagher was born in New York City the grandson of Irish immigrants. He graduated from Iona College and received a Master's Degree in Public Administration from New York University.
In 1999, Meagher graduated from Brooklyn Law School and then began his career in public service. His family played an integral role in his decision to seek out employment with the King's County District Attorney's Office, as both of his grandfathers, his uncles, his father and his brother have all served in the NYPD. In addition to working for the NYPD, Meagher's grandfather and granduncle founded the NYPD's Pipes and Drums Band in 1960. He has carried on that tradition, having taught many of the local Irish pipe bands and individuals in the NYC area. Today, Meagher competes at the top levels of international competition.