In 1870, and again in 1874, he was elected a member of parliament for Maidstone. He lost the seat at the election of 1880; but was at once elected member for the University of London, of which he had been vice-chancellor since 1872. He carried numerous enactments in parliament, including the Bank Holidays Act of 1871 and the Ancient Monuments Act of 1882.
Lubbock was elected the first president of the Institute of Bankers in 1879; in 1881 he was president of the British Association, and from 1881 to 1886 president of the Linnean Society of London. In January 1884 he founded the Proportional Representation Society, later to become the Electoral Reform Society.
In 1865 Lubbock published what was probably the most influential archaeological text book of the 19th Century, Pre-historic Times, as Illustrated by Ancient Remains, and the Manners and Customs of Modern Savages, and was responsible for inventing the names Palaeolithic and Neolithic to denote the Old and New Stone Ages respectively.
He received honorary degrees from the universities of Oxford, Cambridge (where he was Rede lecturer in 1886), Edinburgh, Dublin and Wurzburg; and in 1878 was appointed a trustee of the British Museum. From 1888 to 1892 he was president of the London Chamber of Commerce; from 1889 to 1890 vice-chairman and from 1890 to 1892 chairman of the London County Council.