She was co-credited alongside Gene Markey for writing the original story for Close Harmony (1929) and as composer and production manager for Paramount on Parade (1930).

She and director Edmund Goulding wrote the song "Love, Your Magic Spell Is Everywhere" for Gloria Swanson for her talkie debut film The Trespasser (1929).

Janis's song "Oh, Give Me Time for Tenderness" was featured in the Bette Davis movie Dark Victory (1939), also directed by Goulding.

Before he entered service for World War I, English actor-singer Basil Hallam fell in love with Janis, with whom he had starred in The Passing Show of 1915.

Accompanied by her mother, Janis also took her act on the road, entertaining troops stationed near the front lines – one of the first popular American artists to do so in a war fought on foreign soil.

[7] She wrote about her wartime experiences in The Big Show: My Six Months with the American Expeditionary Forces (published in 1919), and recreated these in Behind the Lines, a 1926 Vitaphone musical short.

A musical about this period of her life called Elsie Janis and the Boys, written by Carol J. Crittenden and composer John T. Prestianni, premiered under the direction of Charles A. Wallace as part of the Rotunda Theatre Series in the Wortley-Peabody Theater in Dallas, Texas on August 15, 2014.