[5] In about 1851, Greenfield began to sing at private parties, debuting at the Buffalo Musical Association under the patronage of Electa and Herman B. Potter.

After her initial success in Buffalo and Rochester, she may have been briefly managed by two African American men from Philadelphia,[6] but in 1851, she took on agent Colonel J. H. Wood, a P. T. Barnum-style promoter and supporter of the Fugitive Slave Act of 1850, who would not allow Black patrons into her concerts.

[1][11] According to an 1853 exposé by Martin Delany, Wood took advantage of Greenfield professionally, handling her money and keeping her in a state of near slavery and isolation.

[9] The day before the concert, the New-York Tribune published "Particular Notice – No colored persons can be admitted, as there has been no part of the house appropriated for them," leading to uproar in the city.

[2] Concert promoter Robert W. Olliver handled the business, and singers Italo Gardoni and Charles Cotton were hired to support her.

Accounts disagree regarding her success in England, with Kurt Gänzl noting "Some versions of 'history' of course, would have it otherwise, and I have read pieces about the lady speaking of her 'popularity' and her 'success' in Britain.

"[14] Sutherland introduced Greenfield to Queen Victoria's Chapel Royal organist, George Thomas Smart.

Harriet Beecher Stowe wrote about Greenfield's appearance before the "elite" English society in "Sunny Memories of Foreign Lands"[17] In the United States, Greenfield reconnected with Wood,[18] though with a strong stance against his discriminatory practices, though circumstances still required her to frequently sing at segregated venues.

Following her return from England, she performed many charity concerts, many supporting Black churches and schools, which were widely popular and raised considerable funds.

In the late 1850s, some of her charitable work became controversial, as she raised money for African missions, expeditions, and aid for Liberian settlers, largely colonialist causes.

[18] Throughout her tours, southern newspapers denied her success or twisted it into pro-slavery propaganda, describing her in grotesquely racist language.

During the American Civil War, she continued performing charity concerts in the North and raised funds to support Black Union soldiers.

She was praised as an exceptional Black achiever, with James McCune Smith claiming "The colored man must do impracticable things before he is admitted to a place in society.

"[18] She was included in each of Philadelphia's Social, Civil and Statistical Association of the Colored People of Pennsylvania's lecture series (likely volunteering her time) as an integral part of the program, and accompanying key speeches.

Notably, she performed preceding a lecture by Frederick Douglass[18] Settling in Philadelphia, Greenfield ran a music studio and promoted Black singers.