George Edgecumbe was born on 4 January 1845 at Chippenham, Wiltshire, England, the son of Martha Eyles and her husband, Henry Edgecumbe, a grocer and later a brewer. After his mother's death from smallpox in 1856, George emigrated to New Zealand with his father and younger brothers. They arrived at Auckland on 23 January 1864 on the John Duncan.
The following year George moved to Ngaruawahia (officially Newcastle until 1878). He was employed by the Auckland merchant W. J. Young for two years, then in 1867 he started on his own as a storekeeper and timber merchant. On 27 April 1871 at Ngaruawahia George Edgecumbe married Annie Hume; they raised six daughters and three sons. George entered local politics as a trustee of the Hamilton West Town Board from August 1871 to July 1872. He became a member of the Town of Newcastle District Board in 1873, and was chairman from 1875 until 1878. In 1876 he advertised his services as an accountant and general commission agent. In the following years he concentrated on developing a career in the newspaper industry, while at various times working as an auditor, real estate agent and commission agent.
In April 1872 Edgecumbe attended a meeting at Ngaruawahia which resulted in the establishment of the Waikato Times by George Jones. In 1877 the Edgecumbe family shifted to Hamilton and the following year George Edgecumbe became business manager of the paper. Although by this time it was owned by the Auckland lawyer and politician F. A. Whitaker and was under the financial control of the Bank of New Zealand, Edgecumbe was able to resist attempts at influence by Auckland big business. He became part-proprietor with Edward Mortimer Edgcumbe in May 1882 and sole proprietor by October 1886. Under his influence the editorial emphasis of the paper became less parochial and more tolerant of change.
It came as a shock when in 1896 the Bank of New Zealand Assets Realisation Board refused to renew Edgecumbe's lease of the newspaper business and instead sold the plant and building to James Shiner Bond. Public sympathy was strongly in Edgecumbe's favour and on 11 July he was able to establish a new paper, the Waikato Argus. He had bought the old Cambridge News plant; now he obtained new premises and managed the enterprise himself until 1901, and again from 1913 to 1914. He retained Henry Holloway from the Waikato Times as editor.
The Liberal Waikato Times and Reform Waikato Argus were in fierce competition for nearly 20 years. However, a low level of business activity, bad debts and wartime conditions affected the profitability of both newspapers. In 1914 Hamilton's mayor, Arthur Manning, approached Edgecumbe and H. J. Greenslade, owner of the Times, to negotiate an amalgamation. The Waikato Times Printing and Publishing Company was formed in late 1915 with Manning as its principal shareholder and managing director. Edgecumbe chaired the board until retiring to Auckland. Thus a new, viable, politically independent Waikato Times emerged.
A contemporary described Edgecumbe as a man of 'medium height, stout with a close-clipped beard and a big nose. He was inclined to be autocratic.' He was also energetic. Through his editorials and his personal efforts Edgecumbe promoted many projects for the advancement of the district. He lobbied for the establishment of Waikato Hospital as a Hamilton borough councillor from 1885 until 1887, assisted at an emergency operation before the facilities were ready, and served on the Waikato Hospital and Charitable Aid Board from 1917 until 1921. During his mayoralty from December 1899 to May 1901 he succeeded in changing the basis of rating to unimproved land value. As a councillor under Mayor James Shiner Bond from May 1905 until May 1907, he endorsed a series of loan polls which saw major works projects started.
A strong sense of public duty imbued most of Edgecumbe's activities. He was a foundation member of the Waikato Chamber of Commerce and sat on a number of committees for the management of local amenities. As a Freemason, for over 13 years he held various offices in Lodge Beta-Waikato. An earnest Anglican churchman, Edgecumbe was closely involved with the administration of St Peter's Church, and in 1886 he successfully led the change from the subscription system to free and open membership.
Edgecumbe was also committed to the cause of education. He sat on the Hamilton West School committee for many years, acting as chairman in 1884, and represented the West Ward on the Auckland Education Board from 1906 to 1914; his main achievement there was the formation of Hamilton High School. He represented the Auckland Education Board on the board of governors, and was elected foundation chairman, serving in that capacity for 10 years.
Edgecumbe had a typically businesslike approach to leisure activities. He organised the Hamilton Boxing Day athletics meetings; re-established the Waikato Rugby Union, and was vice president (1892) and president (1894–1905); founded the Hamilton Cricket Association in 1899; and was active in various other sporting associations. A keen follower of racing and the owner of several horses, he helped establish a racecourse at Claudelands, serving as president or committeeman of the South Auckland Racing Club from 1887 until 1903.
George Edgecumbe was an enthusiastic gardener and orchardist. The apples he grew at his property, The Sycamores, won many prizes at shows throughout the region. He became foundation secretary of the Waikato Horticultural Society in 1884 and was involved in organising exhibitions and marketing fruit. He was appointed to the first general committee of the Waikato Agricultural and Pastoral Association in 1891.
Around 1920 the Edgecumbes retired to Remuera, Auckland, where Annie Edgecumbe died on 28 May 1924. George Edgecumbe died at Remuera on 11 March 1930 and was buried in the same plot as his wife in Hamilton West cemetery. The Waikato Times was his legacy to New Zealand.