According to the Evening Standard, the couple, who started dating in April 2011 and got engaged at the beginning of this year, wed in front of 200 guests in the Nash Conservatory at Royal Botanic Gardens, Kew.
Among those who attended the service were producer William Orbit, Prince Pieter-Christiaan Michiel of the Netherlands and Toseland's friends and former colleagues from the world of motorsport. The singer's representative had earlier confirmed that the wedding would be taking place over the weekend.
Melua and Toseland first met at one of the singer's concerts at Sheffield City Hall. In the past, he has spoken about how the pair supported each other when she decided to take a break from the music industry and he was forced to quit racing after breaking both his wrists.
"Katie has been great," said Toseland. "[At first] she had no interest in me whatsoever because I was a motorcycle racer. She hadn't heard of me. She wouldn't even know what Valentino Rossi looked like.
"It was only because her piano player was such a fan that he kept talking about [meeting me] on the tour bus," he added. "It was nice and a relief for someone so established to be attracted to me because of my personality."
Since her first album Call off the Search debuted at number one in 2003, Melua has gone on to become one of the biggest-selling British female artists of all time. Her latest LP Secret Symphony reached number eight in the UK album charts following its release in March.
Watch the video for Katie Melua's breakthrough hit 'Closest Thing To Crazy' below: