The company, which owns high-end brands such as Cartier, Montblanc and Dunhill London, already has a stake in the YNAP Group but has made a public tender offer to buy the remaining shares at £33.50 per share.
The takeover will only go ahead if it is approved by YNAP Group shareholders.
In a statement is it said that YNAP has waived the standstill obligation included in the shareholder agreement entered into on March 31 2015, which would otherwise prevent Richemont and all its affiliates from purchasing any further ordinary shares of YNAP except in certain circumstances.
Furthermore, an irrevocable undertaking to accept the offer in respect of all of his shares has been received from Mr Federico Marchetti, chief executive officer of YNAP.
Commenting on the offer, Mr Johann Rupert, chairman of Richemont, said: “We are proud to have participated in the growth of Net-A-Porter since its infancy and in the creation of Yoox Net-A-Porter Group, the world’s leading online luxury retailer. With this new step, we intend to strengthen Richemont’s presence and focus on the digital channel, which is becoming critically important in meeting luxury consumers’ needs.”
Rupert added that YNAP would continue to be managed as a separate company, “providing a neutral and highly attractive platform” for luxury brands.