On 4 October 1948, while Bhumibol was driving a Fiat Topolino on the Geneva-Lausanne road, he collided into the rear of a braking truck 10 km outside of Lausanne. He hurt his back and incurred cuts on his face that cost him most of the sight in one eye. He subsequently wears an ocular prosthetic. While he was hospitalised in Lausanne, Sirikit visited him frequently. She met his mother, The Princess Mother Sangwan, who asked her to continue her studies nearby so that the king could get to know her better. Bhumibol selected a boarding school for her in Lausanne, Riante Rive. A quiet engagement in Lausanne followed on 19 July 1949, and the couple married on 28 April 1950, just a week before his coronation.
The marriage took place at Srapathum Palace. Queen Sri Savarindira, the Queen Grandmother presided over the marriage ceremony. Both the king and Sirikit signed on line 11 of their certificate of marriage. As she was not yet 18, her parents also signed, on line 12 directly under her signature. She later received the Order of the Royal House of Chakri, and became queen. After the coronation ceremony on 5 May 1950, both went back to Switzerland to continue their studies, and returned to Bangkok in 1952.