The story is narrated in the first person as an autobiographical memoir told by the titular horse named Black Beauty—beginning with his carefree days as a colt on an English farm with his mother, to his difficult life pulling cabs in London, to his happy retirement in the country. Along the way, he meets with many hardships and recounts many tales of cruelty and kindness. Each short chapter recounts an incident in Black Beauty's life containing a lesson or moral typically related to the kindness, sympathy, and understanding treatment of horses, with Sewell's detailed observations and extensive descriptions of horse behaviour lending the novel a good deal of verisimilitude.

The book describes conditions among London horse-drawn taxicab drivers, including the financial hardship caused to them by high licence fees and low, legally fixed fares. A page footnote in some editions says that soon after the book was published, the difference between 6-day taxicab licences (not allowed to trade on Sundays) and 7-day taxicab licences (allowed to trade on Sundays) was abolished and the taxicab licence fee was much reduced.