Charlotte, 26, who has taken part in the show jumping competition in previous years, chose a smart ivory coloured jacket and matching trousers for the equestrian event on Friday, completing her elegant look with a pair of open-toe tan sandals.
Standing next to her stylish daughter was Princess Caroline of Monaco, who wore a black blazer, a pair of bold, golden trouser and black and gold strappy heels.
The mother and daughter duo laughed and smiled together as they looked on during the podium ceremony before presenting the winners with their trophies.
The following day, Charlotte was joined by Princess Caroline's brother, Prince Albert, which saw the equestrian star slip into a more brightly coloured outfit.
Charlotte, who became an aunt in March when her brother, Andrea Casiraghi and his fiancée Tatiana Santo Domingo, welcomed baby Sacha, wore a striking azure dress and added a touch of sparkle with a pair of dazzling pink and blue earrings.
Prince Albert chose a black jacket, white shirt and green tie for the engagement.
"It's marvellous to be here for another year, in this incredible scene, by the sea in the heart of Monaco," said Charlotte. "Everyone tells me how impressed they after seeing the tournament."
"It is also a privilege to enjoy seeing the best riders in the world," she added, before concluding. "In short, it is a combination of many things that make this a very special event."
Charlotte is currently dating actor Gad Elmaleh, 41. The rugged thespian, who was born in France but resides in the US, first caught the eye of Monaco's beautiful young royal last year and since then their relationship has gone from strength-to-strength with transatlantic visits and most recently a high-profile outing at Monaco's glittering Rose Ball.