Moet-Hennessy Louis Vuitton, the French Champagne and luxury luggage group, declined to comment on details of the sale, but the company said it would expand the shirtmaker's presence in the United States and Europe.
"Thomas Pink is a solid brand that will benefit from the experience of the LVMH group and from new capital that will accompany its growth," said the Louis Vuitton Capital chairman, Daniel Piette.
The firm was established in Chelsea in 1984 by the brothers John, Peter and James Mullen. Thomas Pink quickly became the UK's number one luxury shirt brand through aggressive marketing.
The company was named after an 18th-century tailor in Mayfair whose claim to fame was to make the best hunting coats money could buy, hence the expressions "hunting pink" and "in the pink".
Its core product is the classic hand-made Jermyn Street cotton shirt. The most popular model, the Black Label, sells at pounds 55. The top of the range Sea Island shirt is retailed at pounds 75. The company, said to be planning a share flotation, also offers ties, underwear and accessories for men and women.
Bernard Arnault's rapidly increasing LVMH has become the world's leading luxury goods group. It owns Givenchy, Kenzo, Celine, Parfums Christian Dior and Guerlain. Earlier this year LVMH narrowly failed to take control of Gucci. The Italian fashion giant was rescued by LVMH's arch-rival Pinault- Printemps-Redoute. Less than a month ago LVMH bought the Swiss sport watch maker Tag Heuer for pounds 464m.
There are 20 Thomas Pink shops, including 17 spread across the UK, one in Dublin and two in the US, including the largest shirt store in the world on Madison Avenue, New York. It is almost twice as big as the company's flagship store in Jermyn Street. The company, still run by its founders, also sells through mail order and the Internet. There are some 227 staff and last year, sales reached pounds 24m with pre-tax profit of pounds 2.14m.
Thomas Pink shirts have long been a favourite of City slickers, but many women have also caught on to the tailored shirt look. The company introduced a women's shirt range 12 years ago, which now accounts for 14 per cent of the group's annual sales.
In July, LVMH said sales in the first six months of this year reached 3.59 billion euros (about pounds 2.23bn), rising 18 per cent in the second quarter alone. "We anticipate being able to accelerate the development of Thomas Pink and we are delighted the existing management team will remain," said Mr Piette.
The Thomas Pink chief executive, Des Swan, said:"We believe our partnership with LVMH will yield significant synergies in the roll-out of Thomas Pink worldwide through a variety of distribution channels."
Yesterday, LVMH shares in Paris closed at 287 euros, down 1 per cent.