The company did not provide an explanation for George's resignation, but indicated that it had no plans to fill the vacancy created by his departure at this time.
In May, Chief Executive Fred Green and Chairman John Cleghorn both quit after a boardroom coup, a rarity in Canada's conservative corporate culture, following a proxy battle with New York activist shareholder William Ackman and his company Pershing Square Capital Management.
Ackman, who is Canadian Pacific's largest shareholder with a 14 percent stake, had been campaigning since January to unseat Green, arguing that only new leadership could improve the railroad's operating efficiency - a key industry metric.
All seven members of Ackman's slate were elected to Canadian Pacific's board at an annual shareholder meeting on May 17. In addition to Cleghorn and Green, four other directors opted not stand for re-election on the day.
Earlier this month, David Raisbeck, who had been a board member since 2009, also resigned, citing personal reasons.
George recently retired from his position as chief executive at Canada's top oil producer and refiner, Suncor Energy. He had joined Canadian Pacific's board roughly a year ago, in May 2011.
"The board wishes to thank him for his many contributions to the company, particularly his leadership in the board's search for a new CEO," Paul Haggis, chairman of Canadian Pacific's board, said in a statement.
Stephen Tobias, a rail industry veteran and Canadian Pacific board member, has being acting as the company's interim CEO since Green's departure in May. The company did not indicate when it intends to name a new permanent replacement. (Reuters)
