The actor - who has the title role in the hit wizarding movie franchise - was named fifth richest in the young millionaires category , with a fortune of Â£42 million, and his co-star Emma Watson, who plays Hermione Granger, was placed joint 10th with a Â£22 million fortune.
Former 'Harry Potter' actor Robert Pattinson, who has gone on to find success as the star of the 'Twilight' series of films, is placed 14th on the list with a Â£13 million fortune.
The top spots on the young millionaires list were taken by inheritors and businessmen.
A source said: "The 'Harry Potter' franchise has been massively successful worldwide and boosted the UK economy, taking hundreds of millions at the box office. Five of the franchises films are in the top twenty highest grossing of all time and although its stars were just children when it started I don't think anyone could have guessed exactly how successful this was going to be. They have all still worked very hard for their places on this list, and it shows the once again healthy state of the British film industry."
J.K. Rowling, who penned the series of children's books the movies were based on, topped the author's list with a fortune estimated at Â£519 million.
In the main list of Britain's 1,000 richest people, Lakshmi Mittal and was named the country's most wealthy, with a fortune of Â£22.45 billion, which has more than doubled in the last year from Â£10.8 billion.
Sunday Times Rich List: Top 20 young millionaires:
1 Arthur Landon, 28, inheritance Â£200m
2 Andrew Michael, 30, internet Â£130m
3 Fawn, 24, and India Rose James, 18, inheritance Â£120m
4 Richard Walters, 30, construction and mining Â£98m
5 Daniel Radcliffe, 20, films Â£42m
6 Sean O'Connor, 29, finance Â£33m
7= Kiera Chaplin, 27, media Â£28m
7= Keira Knightley, 25, films Â£28m
7= Princes William, 27, and Harry, 25, land and inheritance Â£28m
10= Adam Hildreth, 25, software Â£22m
10= Emma Watson, right, 20, films and modelling Â£22m
12 Rupert Grint, 21, films Â£20m
13 Richard Jones, 27, internet Â£15m
14 Robert Pattinson, 23, films Â£13m
15 Natalia Vodianova, 28, modelling Â£12m
16= Charlotte Church, 24, music Â£11m
16= Katherine Jenkins, 29, music Â£11m
16= Leona Lewis, 25, music Â£11m
16= Earl of Shaftesbury, 30, land Â£11m
20= Cheryl Cole, 26, music Â£10m
20= Dominic McVey, 25, publishing and property Â£10m
20= Katie Melua, 25, music Â£10m