In 1836, when he was only sixteen years old, Jared exhibited a portrait of his father in the National Academy and was favorably noticed by the critics.

Jared pursued the study of theology at intervals with his art, and, in 1854, he entered the ministry of the Protestant Episcopal Church.

[1] Flagg served as an Episcopal minister for a decade, including as Rector of Grace Church Brooklyn Heights,[4] until he resumed the practice of his art.

Among Flagg's more notable portraits are of several of the judges of the New York Court of Appeals, including a three-quarter length of Chief Justice Sanford E. Church (which was placed in the new state capitol); Rhode Island Governor Daniel Russell Brown (which was placed in the Rhode Island State House); an 1887 life-size full-length portrait of William M. Evarts (which also hung in the capitol; and several portraits of Commodore Vanderbilt (one of which hangs in the directors' room at the Grand Central depot in New York); and William H. Vanderbilt, among others.

[1] Other notable paintings by Jared Flagg include Holy Thoughts and Paul before Felix (1849), and Angelo and Isabella (1850).