After an arm injury ended her aspirations as a pianist, Jenkins gave piano lessons at her apartment in Philadelphia, The Newport, built in 1897.

[13] In 1909, in her early forties, Jenkins met a 33-year-old British actor named St. Clair Bayfield (1875–1967); they began a vaguely defined cohabitation relationship that continued the rest of her life.

[20] Upon her father's death later that year,[11] Jenkins became the beneficiary of a sizable trust, and resolved to resume her musical career as a singer with Bayfield as her manager.

As the "chairman of music" for many of these organizations, she began producing lavish tableaux vivants, popular diversions in upper-crust social circles of that era.

In recordings, her accompanist Cosmé McMoon can be heard making adjustments to compensate for her constant tempo variations and rhythmic mistakes,[25] but there was little he could do to conceal her inaccurate intonation.

[28] The question of whether "Lady Florence"—as she liked to be called, and often signed her autographs[20]—was in on the joke, or honestly believed she had vocal talent, remains a matter of debate.

On the one hand, she compared herself favorably with renowned sopranos Frieda Hempel and Luisa Tetrazzini, and seemed oblivious to the abundant audience laughter during her performances.

"[27] Despite her careful efforts to insulate her singing from public exposure, a majority of critics favored the view that Jenkins's self-delusion was genuine.

"[20] As an anonymous obituary writer later put it, "Her ears, schooled in constant introversion, heard only the radiant tones which never issued forth to quell the mirth of her audiences.

"[22] Her recitals featured arias from the standard operatic repertoire by Mozart, Verdi, and Johann Strauss; lieder by Brahms; Valverde's Spanish waltz "Clavelitos" ("Little Carnations"); and songs composed by herself and McMoon.

Her fans, aware that "Clavelitos" was her favorite song, would usually demand an encore, prompting her to send McMoon into the audience to retrieve flowers, basket, and castanets so that she could sing the number again.

[28] At the age of 76, Jenkins finally yielded to public demand and booked Carnegie Hall for a general-admission performance that took place on October 25, 1944.

[28] Numerous celebrities attended, including Porter, Marge Champion, Gian Carlo Menotti, Kitty Carlisle, and Lily Pons with her husband, Andre Kostelanetz, who composed a song for the recital.

McMoon later recalled a moment: "[When she sang] 'If my silhouette does not convince you yet / My figure surely will' [from Adele's aria in Die Fledermaus], she put her hands righteously to her hips and went into a circular dance that was the most ludicrous thing I have ever seen.

"[29] Five days after the concert, Jenkins suffered a heart attack while shopping at G. Schirmer's music store, and died a month later on November 26, 1944, at her Manhattan residence, the Hotel Seymour.

[29] Some of Jenkins's performance difficulties have been attributed to untreated syphilis, which causes progressive deterioration of the central nervous system in its tertiary stage.

[33] Nerve damage and other morbidities caused by the disease may have been compounded by toxic side effects—such as hearing loss—from mercury and arsenic, the prevailing (and largely ineffective) remedies of the pre-antibiotic era.

[22] The selections include four coloratura arias from operas by Mozart, Delibes, Johann Strauss II, and Félicien David, and five art songs, two written for Jenkins by her accompanist, Cosmé McMoon.

[35] The material has since been reissued in various combinations on four CDs: Jenkins commissioned filming of her performances at the Verdi Club's signature annual event, the "Ball of the Silver Skylarks", held each October at the Ritz Carlton Hotel.

[38] Jenkins historian Donald Collup presented excerpts from the films in a 2016 YouTube video [39] and announced plans to produce a documentary, which as of 2025[update] had not been released.