Gilbert Francis Molyneux Ogilvy was born on 9 April 1868, the fourth son of Sir Reginald Ogilvy, 10th Baronet of Inverquharity and Baldovan and his wife the Hon Olivia Kinnaird, daughter of the 9th Baron Kinnaird. He was educated at Glenalmond and at University College, Oxford, before being articled to Hippolyte Jean Blanc in Edinburgh: his nomination paper does not give dates, but the connection presumably came through All Souls Church at Invergowrie, built in 1890-93 for Lady Frances Kinnaird.
In or about 1898 Ogilvy entered into partnership with Percy Benjamin French Freeman (born 1859). Freeman had been articled to Robert Henry Burden in London from 1879 until 1883. Thereafter he obtained an appointment as clerk to George Gilbert Scott, Junior, and together with Temple Moore coped with Scott's mental breakdown in 1883-84. When Scott's practice closed he became assistant to Bodley & Garner, setting up his own practice at 3 Staple Inn, London c.1885. The arrangements there were highly unusual as a large part of his business was acting as office manager for Temple Moore. As Giles Gilbert Scott later wrote, 'Moore did not have an office in the ordinary sense as he always worked in his private office at his own home in Well Walk, Hampstead. I did not therefore work under his immediate supervision, but in an office in Staple Inn under the rule of Mr P B Freeman, who was associated with five other architects, all carrying on their own practices.'
Ogilvy's practice consisted principally of estate work and private houses. The estates on which he worked comprised Baldovan, which his elder brother, Sir Herbert Kinnaird Ogilvy 12th Bt WS of the Dundee legal firm of Shiell & Small inherited from their nephew in 1914; the Guthrie estate of Craigie, Angus (now Dundee( for which Sir Herbert was factor; Winton, East Lothian which was owned by his aunt Mrs Nisbet Hamilton Ogilvy; Landguard, Isle of Wight; Sudbury, Derbyshire; Langford, Oxfordshire; Greystoke Castle, Cumberland; Hatherop Castle, Gloucestershire; and the Duchy of Lancaster.
Freeman and Ogilvy were both admitted LRIBA in 1911, Freeman on 27 February and Ogilvy on 20 July. Freeman's proposers were Temple Moore, William Newton Dunn and William Bonner Hopkins, also from Bodley's office; Ogilvy's were Henry Martineau Fletcher, Godfrey Pinkerton and William Dunn, all of London. By that date, some time after 1904, the firm had moved to 6 Gray's Inn Square.
In 1912 Ogilvy married Marjory Katharine Clive, the daughter of Meysey Clive of Whitfield, Herefordshire. He was then living at 17 Kent Terrace, Regent's Park; after his marriage he moved to The Glade House, Burgh Heath, Surrey, but in the early years of the First World War the London practice closed, and Ogilvy returned to Dundee in 1919 to develop the Baldovan estate, setting up practice within his brother Herbert's office at 5 Bank Street. In 1920 he inherited Winton from his aunt but he continued his Dundee practice, merging it in 1925 with that of Nelson T Stewart of the joiners and builders John Stewart & Sons of 16 Forfar Road, a firm which specialised in shop and office fitting and had provided a design and build service since about 1911. This partnership took the name of Ogilvy & Stewart. Both Ogilvy's son, Sir David Ogilvy, and Henry Pearce Robbie observed of this practice that Stewart did not have much design sense but was a sound practical man from his experience in his father's business, and that Ogilvy's interest in the firm was at times ephemeral: he tended to undertake only commissions in which he had a personal interest, leaving the rest to Stewart whose drawings he sometimes tidied up. Meanwhile, the practice of Freeman & Ogilvy returned to business after the war and was still active in the mid-1920s; it is not clear whether Ogilvy retained an interest in it or whether it was only the practice title itself that was continued.
After only three years, in 1928 the practice of Ogilvy & Stewart was merged with that of James Findlay and David Smith. Gilbert Ogilvy then withdrew, observing that the recession was so severe it was wrong to deprive other architects of a living by continuing a practice he could afford to do without.
Ogilvy lived mainly at Winton thereafter. He died at Aviemore on 17 June 1953. He was survived by his son Sir David who inherited the baronetcy from his uncle, another son and three daughters.