In 1906 Okotoks enjoyed telephone service and electric lights. Natural gas arrived in 1912, but it wouldn't be until 1952 that residents were able to enjoy a public waterworks and sewer system. Like many small prairie towns, fires and floods plagued Okotoks in the early years. The Sheep River flooded its banks in 1902, 1915, 1940, and 1963, among others. Many of the town's early buildings were lost to fire and whole blocks burned at times. When oil was discovered in Turner Valley in 1914, Okotoks quickly became a regional oil distribution centre. It earned the title "Heart of the Oilfields" because equipment stopped on the rail line in Okotoks before completing its road journey to Turner Valley.
For the most part, Okotoks remained unchanged through the first half of the century, with the population settling around 600 people. Wooden sidewalks and hitching posts were removed in the late 1920's; men left to fight in the first and second world wars, and residents endured the Depression. The economic upturn came in the late 1970s. The population doubled to 1,928 people in 1976 and it has continued to double approximately every 10 years.
In 2004, the Town of Okotoks celebrated its 100th anniversary. That year, Okotoks was home to 12,187 residents. The most recent municipal census, conducted in 2014, shows the population has more than doubled to 27,331.