The name Keely is an English feminine given name, originally a diminutive form of the name Cecilia. The name Cecilia itself is derived from the Roman family name Caecilius, which is of uncertain etymology but may be related to the Latin word "caecus," meaning "blind."

In the early Christian era, the name Cecilia became associated with the legendary Saint Cecilia, a Roman martyr who is the patron saint of music and musicians. This association likely contributed to the popularity of the name Cecilia and its diminutive forms, including Keely, in the Christian world.

The earliest recorded use of the name Keely dates back to the 16th century in England. One of the earliest known bearers of the name was Keely Halford, an English poet who lived in the late 16th and early 17th centuries.

Over the centuries, several notable individuals have borne the name Keely. In the 19th century, Keely Stokes (1825-1900) was a British artist and illustrator known for her watercolor paintings. Keely Smith (born 1928) is an American jazz singer who rose to prominence in the 1950s and had a successful career spanning several decades.

Keely Shaye Brosnan (born 1963) is an American journalist and author, best known as the wife of actor Pierce Brosnan. Keely Hodgkinson (born 1992) is a British middle-distance runner who won a silver medal in the 800 meters at the 2020 Tokyo Olympics.

Keely Cashion (born 1973) is an American singer-songwriter and multi-instrumentalist, known for her work in the indie rock scene. She has released several critically acclaimed albums and has collaborated with various artists.

While the name Keely has its roots in the ancient Roman world, it has evolved over time and has been embraced by different cultures and societies. Its association with Saint Cecilia and its historical significance have contributed to its enduring popularity as a given name for girls.