He is second only to pop queen Adele - who has seen her fortune swell by around 50% in a year when she released no new material - who tops the Sunday Times Rich List's countdown of the biggest financial successes in the music world aged 30 and under.
Superstar Scottish DJ Harris has had a string of major hits with nine top singles from his latest album 18 Months and has worked with acts such as Cheryl Cole, Rihanna and LMFAO. Last year he was named songwriter of the year at the Ivor Novello Awards.
The former shelf-stacker - whose real name is Adam Richard Wiles and who is dating Rita Ora - is said to be able to command £100,000 for a night's work as a DJ in Las Vegas.
Cole, who has recently signed up for a return to The X Factor panel, drops to third place from last year's number two although she has banked a further £2 million, according to the compiler of the list, Philip Beresford.
The five members of One Direction take joint fourth place with an estimated £14 million each, although they have a combined fortune of £70 million. Niall Horan, Zayn Malik, Harry Styles, Louis Tomlinson and Liam Payne are thought to have seen their finances swell by £9 million in the past 12 months, which has seen them tour, release a movie and a third album.
Their inclusion in the upper reaches of the list - along with Mumford And Sons frontman Marcus Mumford and his wife Carey Mulligan, together worth £13 million - has edged out regular faces such as Katie Melua and Charlotte Church.
Melua has slipped from last year's joint-third spot to number 11, while Church drops from sixth to 15th place.
Young entrepreneur Jamal Edwards, 23, has made it to number 15 with his £8 million fortune amassed from his broadcasting and production company SB.TV which emerged from the grime and hip-hop scene.
The full Rich List is published in this weekend's Sunday Times.
:: Top ten (with previous ranking and 2013 wealth estimate, where applicable, in brackets)
1 (1) Adele - £45m (£30m)
2 (new) Calvin Harris - £30m (-)
3 (2) Cheryl Cole £16m (£14m)
4= (17=) Niall Horan £14m (£5m)
4= (17=) Zayn Malik £14m (£5m)
4= (17=) Liam Payne £14m (£5m)
4= (17=) Harry Styles £14m (£5m)
4= (17=) Louis Tomlinson £14m (£5m)
9= (3=) Leona Lewis £13m (£12m)
9= (-) Marcus Mumford and Carey Mulligan £13m (-)