He wrote for The Saturday Evening Post and started The Town Crier newspaper of West Haven, Connecticut in 1930.
The following year he was moved to New York, serving until 1943 as a roving reporter and special assignment writer for INS, during which he spent a remarkable New Year's Eve with British Prime Minister Winston Churchill on a train ride from the United States to Canada during World War II.
In 1942, he co-authored with another noted columnist, Damon Runyon, The Life Story of Captain Eddie Rickenbacker As heard at The Paley Center for Media (formerly The Museum of Television and Radio), Kiernan's animated reporting and analysis of V-E Day in 1945 remains one of the era's most stirring historical recordings.
On ABC Radio in 1948 he had a chat program called That Reminds Me, with former New Jersey Governor Harold Hoffman and "Uncle Jim" Harkins.
After the relative success of Stroke of Fate, he began co-hosting NBC Radio's long-running news magazine, Monitor.