Emily Smith was a first generation American, born in New York City to British father John Henry Smith and French mother Emily Viehl Onderdonk. She was the oldest of three surviving daughters, including Verene R. (3/1882) and Annice (3/1885). Four other siblings died at a young age. Her father died some time before 1900. As she was growing up Emily received training in voice and piano, possibly from her mother who worked as a music teacher at some point, and sang with the Grace Church Choir, as well as some concerts as a featured contralto. She was also known to be a capable accompanist.

In the mid-1890s Emily began writing songs with lyricist Harry S. Miller among others. He had done well with his big hit The Cat Came Back. However, they appeared to be selling their works one at a time to various publishers without a contract. One of their joint submissions, Down Old New England Way, was published by New York's March King, Edward Taylor Paull, as was a subsequent march by Smith, Arizona, which saw at least two printings, the second in a new arrangement by Paull. There is some implication that she may have worked for the E.T. Paull Publishing Company for a time.

For the 1900 census Emily was shown as living with her widowed mother and her sisters in Manhattan, listed as a composer of music. Her younger sisters Verene and Annice were also involved in the music business, but in sheet music sales, not as composers. Emily was hired in the summer of 1900 by the Lyric Music Company to compose and arrange for them, followed by a stint with the newly formed Peerless Publishing Company in 1901 who reissued one of her earlier copyrighted songs, You are Not the Girl I Loved Long Ago, a minor hit that year. By the time of the 1905 New York State census, the Smiths were living in the Bronx, New York, where most would remain for the rest of their lives, and were working as music teachers.

Emily composed over two dozen songs and instrumentals, even providing her own lyrics for a few of them. Her pieces appeared sporadically throughout the decade, including several under the lesser-known Star Music Company imprint. with the last known publication, Dainty Princess: Three Step, appearing under the Sam Fox imprint in Cleveland, Ohio. It is possible she worked as an arranger or promoter for Fox in his Manhattan office.

For the 1910 census Emily was living north of Manhattan in the Bronx, along with her mother and her sister Verene, but having removed some fourteen years from her actual age (Verene deducted six). Both sisters were working as musicians from their home. Annice had been married the year before in a story that caught the fancy of the public and mentioned Emily. A young architect and artist of Japanese and French extraction had seen her and wanted to sketch Annice. In a few weeks Gilbert James Fudji's interest in Annice blossomed to the point of a romance and wedding that became a story which was actually printed in syndication outside of New York as well.

Traces of Smith disappear after her 1911 waltz Dainty Princess: Three Step. She died in late 1914, although the cause of her demise at age 42 was not specified. Emily is interred at Cedar Grove cemetery in Bronx, New York.