Professor Hillis, 70, worked with the Scottish Football Association for almost 40 years but passed away last month following a short battle with cancer.
Yesterday Sir Alex Ferguson, Rangers manager Ally McCoist, and former Scotland boss Craig Brown gathered at Wellington Parish Church in Glasgow to attend a thanksgiving service.
More than 350 family and friends were also joined by ex-Celtic star Murdo McLeod and Gerry McCann, the father of missing girl Madeleine, who had known Prof Hillis from his time working as a doctor in Glasgow.
The medic worked under eight national coaches and was on hand to treat former Scotland manager Jock Stein when he suffered a fatal heart attack in 1985.
The father of four also served with footballing bodies Uefa and Fifa.
The service heard Sir Alex praise Prof Hillis's professionalism when he tried to save the life of Stein
He was also instrumental in introducing a heart screening programme for footballers after a number of tragedies involving players.
Prof Hillis, who died on July 21, is survived by his wife Anne, daughter Sara, sons Andrew, Ally, and Iain, and 10 grandchildren.