Southcott was born in Panorama, South Australia, and attended Paringa Park Primary School, and St Peter's College.

He defeated Senate leader and future Defence Minister Robert Hill, a moderate, in a pre-selection battle for the seat of Boothby in 1994.

Resulting from the ascendancy of Malcolm Turnbull at the 2008 Liberal leadership ballot, Southcott became Shadow Minister for Employment Participation, Training and Sport.

Following the resignation of Bronwyn Bishop, Southcott ran for the position of Speaker of the Australian House of Representatives in August 2015 but was unsuccessful.

[11] The Liberals pre-selected doctoral student and newspaper columnist Nicolle Flint as their candidate in Boothby at the 2016 election.