From 1951 to 1966, Connolly was a gossip columnist for The Hollywood Reporter, a daily entertainment newspaper dealing with film and television productions, located in Los Angeles, California.
The screenplay for the biographical film I'll Cry Tomorrow (1955) was based on the autobiography of the same name by actress Lillian Roth, that was written in collaboration with Connolly and Gerold Frank.
He was described by Newsweek as "probably the most influential columnist inside the movie colony," the one writer "who gets the pick of trade items, the industry rumors, the policy and casting switches."
Actress and writer Shirley MacLaine devoted several pages in her first memoir, Don't Fall Off the Mountain (1970), to an incident in which she had marched into the offices of The Hollywood Reporter and punched Connolly in the mouth.
The full story appeared on page 5 under the headline “Shirley Delivers A Punchy Line” with the byline of Bernard Lefkowitz, who later in the 1960s became an acclaimed author of non-fiction books.