The British actress and the billionaire entrepreneur originally split in January 2012, but remarried in July 2013.
However, the pair have decided to go their separate ways once again after almost 18 months of marriage, reported Independent.
Musk filed for divorce at the Los Angeles County Superior Court on December 31.
A joint statement from the pair explained that the split was amicable and that Riley will receive 10 million pounds in cash and other assets, as per their prenuptial agreement.
Riley has starred in 'Inception', 'St Trinians and The Boat That Rocked', and recently wrote and directed her first feature film.