The son of William Alston, he was born in All Saints' Waccamaw Parish in Pawleys Island, South Carolina.

In 1805, the House of Representatives chose Alston to be the Speaker, and he pushed the legislature to adopt a more equitable basis of representation.

In 1812, the General Assembly elected Alston to be the Governor of South Carolina for a two-year term, after the removal of Thomas Sumter and Andrew Pickens as candidates.

With the War of 1812 raging, Governor Alston called the state militia into service in 1813, to protect military magazines from the British.

Subsequently, Alston dismissed the entire militia from service; but the residents were in shock that their state was then completely defenseless from British attack.