The Scots actor has seen his earnings rise since gathering a global following playing Highland warrior Jamie Fraser in the drama.
The ‘Outlander effect’ has been credited with boosting Scotland's economy with fans flocking to see historic sites used as filming locations for the show.
And it seems its popularity has also boosted Heughan’s bank balance after his company posted an impressive set of results.
Accounts filed at Companies House for his firm Cairn Mor Creative show it had total assets of £4,045,268 for 2020.
After paying off creditors to the tune of £672,582, the company reported shareholder funds of £3,372,686.
That is a rise of more than £2 million on the previous year when the firm was valued at £1,305,036. In 2016 it was worth just £87,625.
Heughan, 40, set up the company, which is based in Surrey, in April, 2015, after he finished filming the first season of Outlander. The nature of the business is listed as 'performing arts'.
Heughan plays charismatic Highlander Jamie Fraser in the show, which charts the adventures of Claire Randall, a former Second World War combat nurse played by Irish actress Caitriona Balfe.
Randall is on a second honeymoon to Scotland with her husband Frank in 1945 when she is mysteriously transported back in time to 1743. It is here, on the cusp of the Jacobite rising, that she meets the dashing Fraser.
Heughan, who was born in New Galloway, Dumfries and Galloway, spent his teenage years in Edinburgh before going on to study at the Royal Scottish Academy of Music and Drama in Glasgow.
His part in David Greig's Outlying Islands in 2002 saw him nominated for a Laurence Olivier Award as most promising new performer.
Other early roles included parts in River City, Midsomer Murders and the BBC soap opera Doctors, before Heughan landed his big break in Outlander in 2013.
Heughan's most recent role was in the action thriller SAS: Red Notice and he has been tipped as a contender for the part of James Bond when Daniel Craig steps down as 007.
Filming on the sixth series of Outlander started in February after lengthy delays due to the coronavirus pandemic.