Giovanni Battista Bononcini (18 July 1670 - 9 July 1747) was an Italian Baroque composer and cellist, one of a family of musicians. His father, Giovanni Maria Bononcini, was a violinist and composer.
Bononcini the younger was born in Modena.
His works include a number of operas, masses, and a funeral anthem for the Duke of Marlborough. One of his operas was Serse, later adapted by George Frideric Handel. He played cello and published his earliest works for this instrument in 1685 at Bologna.
Bononcini was for a time maestro di cappella at San Giovanni in Monte and afterwards worked in Milan, Rome, Vienna, Berlin, and from 1720 to 1732, in London, where he rivalled Handel for a time. He left after charges of plagiarism were proven against him, and died in poverty in Vienna. His younger brother, Antonio Maria Bononcini, was also a composer.