Mount Colah is an outer suburb of Northern Sydney, in the state of New South Wales, Australia 24 kilometres north of the Sydney central business district, in the local government area of Hornsby Shire.

Mount Colah is 5 km north of Hornsby, the nearest major town centre.

In the process it cut through an old World War II gravel airstrip, and isolated 2 holes of the Asquith Golf Course just to the south.

Mount Colah was voted "Australia's Best Suburb" through an online poll conducted by Ninemsn in 2010.

Other languages spoken at home included Mandarin 3.9%, Persian (excluding Dari) 2.3%, Hindi 1.4%, Cantonese 1.3% and Spanish 1.1%.

The suburb of Mount Colah embraces Bobbin Head commercial area, which has cafes, tourist information and a marina, with a large boat ramp in Appletree Bay.

The group includes a variety of small retailers, restaurants and food stores, as well as a truck stop that has been servicing locals and truck drivers detouring from the F3 since the 1950s, plus a doctor's clinic, dental clinic, newsagent and a pharmacy that combines postal services.

The school hall acts as the suburb's polling place for voting in local, state and federal elections.

Other similar street names there include Red Cedar Drive, Acorn Place and Chestnut Road.