He was born in Vallenar on February 2nd, 1842; son of John Ashley Walker and Mercedes Martinez Soria.
He studies at the Sacrados Corazones (Sacred Hearts) school in Copiapo and then at the San Ignacio school in Santiago. He became a lawyer at the Universidad de Chile in 1866.
That same year he embarked aboard a Navy ship in the middle of the war against Spain. In 1867 he was sent to Bolivia as secretary of the Chilean legation. He returned in 1868, and took a trip through Europe and the United States.
Once back in the country, he began his political career, becoming one of the youngest leaders of the Conservative party.
In 1869 he was section head of the Ministry of the Interior, and the following year he became deputy for Vallenar until 1873. When he finished his term, he went to Bolivia as head of business (1873-1875). Upon completing this task, he embarked on a journey to Europe.
When he returned to the country, he completely devoted himself to politics.
He was elected deputy for Vallenar (1873-1876), then for Santiago (1879-1882). In 1885, he was elected deputy for Maipo, and in 1888, he was elected to another term. Between 1891 and 1894 he was deputy for Rancagua, Cachapoal and Maipo.
When revolution against the government of Jose Manuel Balmaceda broke out, Walker Martinez was one of the leaders of the conservative Commission, which was formed after the suspension of extraordinary sessions in Congress. This way, in clandestinity, he organized and encouraged activities (some of them subversive) for the member of the Revolutionary Committee in Santiago.
In addition, in 1891, he signed Balmaceda’s letter of dismissal. After the civil war, he returned to the Senate in representation of Santiago (1894-1897) and was reelected to two more terms. He was unable to complete his final senatorial term because he passed away on October 5th, 1905.