He was educated at Eton and Christ Church, Oxford, where he graduated BA in 1828. While at college his interest in geology was aroused by the lectures of William Buckland, and by his acquaintance with William D. Conybeare.
Subsequently when travelling in Switzerland with Lord Cole (later to be 3rd earl of Enniskillen) they were introduced to Prof. L Agassiz at Neufchâtel, and determined to make a special study of fossil fish. During the course of fifty years they gradually gathered together two of the largest and finest of private collections—that of Sir Philip Grey Egerton being at Oulton Park, Tarporley, Cheshire.
Egerton described the structure and affinities of numerous species in the publications of the Geological Society of London, the Geological Magazine and the Decades of the Geological Survey; and in recognition of his services the Wollaston medal was awarded to him in 1873 by the Geological Society. He was elected Fellow of the Royal Society in 1831, and was a trustee of the British Museum.
As a Member of Parliament he represented the city of Chester in 1830, Cheshire South from 1835 until 1868, and West Cheshire from 1868 to 1881. He died in London on April 6 1881. His collection of fossil fishes is now in the British Museum. He is commemorated in the name of the Rusty-fronted Barwing Actinodura egertoni.