[citation needed] Before she became a Mack Sennett bathing beauty, Hill worked as an artist's model in New York.

Thelma and her mother moved to California, where they opened a cafe down the road from the Sennett studios.

[citation needed] She started working as an extra at the Sennett studios in 1919 and appeared in dozens of comedy shorts including Picking Peaches (1924) and The Hollywood Kid (1925).

Hill starred opposite Ben Turpin in A Prodigal Bridegroom (1926) and with Billy Bevan in Hoboken From Hollywood.

From 1927 to 1929, she co-starred with Bud Duncan in Larry Darmour's series of silent Toots and Casper comedy shorts and was Laurel and Hardy's leading lady in Two Tars (1928).

After having a nervous breakdown she entered Edward Merrill Sanitarium in Culver City, California, in early 1938.