The ad uses a photograph catching Phillips mid-jump while riding her horse Toytown. The copy reads: "Handles beautifully, wonderful temperament, no refusals", referring to Phillips and Land Rover's vehicles.
Phillips made news as the first member of the Royal family to star in an advertising campaign after being signed up by Land Rover last year. In January, an ad was unveiled showing the Queen's granddaughter staring into the camera in a long mud-splattered Roberto Cavalli dress with a plunging neckline, under the slogan "Beautifully poised".
Andy Griffiths, Land Rover UK's marketing director, said: "The second ad takes us to the heart of Zara's skills in eventing, clearly encapsulating her true determination as a sportswoman who is at the top of her game.
"She is the embodiment of 'Go beyond' and we are very proud of our ongoing association with her as a Land Rover brand advocate."
Land Rover is the official sponsor of the British Three-Day Eventing and The Land Rover Burghley Horse Trials.