A native of Hartford, Connecticut, after graduating from St. Paul's School,[1] Welch attended Yale and Columbia University.

After spending four years on the legitimate stage, Welch started his screen career appearing with World Film Corporation, Universal, Pathé Studios and Goldwyn Pictures.

Among his earliest works were two Thomas Ince productions, Stepping Out and The Cup of Life, followed in rapid succession by Miss George Washington, with Marguerite Clark; The Courage of Marge O'Doone, with Pauline Starke; and with Grace Darmond[citation needed] in The Gulf Between (1917), the first feature film produced in the two-strip version of Technicolor.

[4] During World War II, he made foreign-language broadcasts for the Voice of America (VOA), using his fluency in French and German.

In 1945, a door at the VOA studio in New York hit Welch on his forehead, causing both retinas to detach.