Born at Loyal Hill (in the area of Summerville) in Hants County, Nova Scotia, the son of John Nutting and Margaret (MacCallum) Grant, Grant was educated in Newport, Nova Scotia. He commenced his business career with S. A. White & Co, in 1873. He was a member of the firm Black Bros. Co. from 1875 to 1893. He then formed the firm Grant, Oxley & Company. Grant, Oxley & Company merged with Alfred J. Bell & Co. Ltd. in 1964 and still operates today under the name of Bell & Grant Insurance.
A portrait of the Honourable MacCallum Grant by Henry Harris Brown was donated to the Art Gallery of Nova Scotia in 2006 by Grant's granddaughter, Margaret H. Grant. The portrait was unveiled by the 30th Lieutenant Governor of Nova Scotia, the Honourable Myra Freeman. The portrait is on loan to Government House (Nova Scotia) and can be viewed there in the ballroom.