Other equestrian ambassadors for the car brand include Zara Tindall and Nick Skelton.
Todd lives near Swindon in the UK and after four decades is still competing internationally. He will continue in top-level competition this year including the Land Rover Burghley Horse Trials, which he has already won five times.
He said the trials had always been his favourite event.
"It comes at the end of the season and everyone looks forward to it. Of all the four-star events, it has the most relaxed and friendly atmosphere.
"The cross-country course is spectacular, with iconic fences like the Land Rover Discovery Valley and Cottesmore Leap. I absolutely love competing there."
Former All Black Dan Carter was also a Land Rover ambassador until February this year when he was dropped following a drink-driving incident in France.