Meghan was cheered by well-wishers at the Los Padres charity polo match in Santa Barbara after pecking each team member on the cheek - before kissing her husband.
The duchess, who was wearing a black hat, a polka dot blouse and white shorts, realised some of her lipstick had rubbed off and gave Harry’s lips a wipe as onlookers watched.
The match raised funds for several local charities tackling causes such as food poverty, mental health and climate change, including Food Bank Santa Barbara County, Heal the Ocean and CALM4kids.
The event was watched by celebrities including Rebel Wilson.
Prince Harry, 37, has played polo all of his life and joined matches with the Los Padres polo team recently. The club is run by his friend and sportsman, Nacho Figueras, who has been dubbed the ‘David Beckham of polo’.
It comes as the couple prepare to travel to the UK for the Queen’s Platinum Jubilee celebrations at the start of next month.
They will take their children Archie, three, and Lilibet, 11 months, for the journey, with Lilibet still yet to meet the British side of her family.
Meghan and Harry are not expected to make an appearance on the Buckingham Palace balcony during the opening celebrations on June 2, as the palace has said this is only for “members of the Royal Family who are currently undertaking official public duties".
Speaking last week, Prince Harry said he hopes his children “never have to experience the online world as it exists now” as he criticised social media companies that make “unimaginable money” from people’s time, attention and information.
Harry spoke at the launch of the 5Rights Foundation’s Global Child Online Safety Toolkit over video link from his home in California and hailed the organisation’s work in calling for a safer digital world for young people.