Gad, who is usually spotted at high-profile events with Charlotte and her famous relatives, was nowhere to be seen at the glittering soirée.
It looks like the French comedian had to bow out of the ball due to an illness, judging by his recent Twitter posts.
Gad Elmaleh explained that he had the flu on the day of the Rose Ball
Sharing a photo of himself lying in bed and sporting a sad face, Gad captioned the snap "Back from Pattaya, la grippe m'a accueilli à l'aéroport #meskine #aulit #frissonette :(" explaining that he had the flu.
The 43-year-old, who returned from the Thai beach resort on the day of the ball, followed it up with another post the next day. "I'm sick of the phrase 'There's nothing you can do about flu' – I have stuff to do!" Gad wrote in French, showing his frustration.
The actor, who lives and works in France, wasn't the only notable absentee from the annual Rose Ball held in Monte Carlo.
Charlotte Casiraghi and her future sister-in-law Beatrice Borromeo partied the night away with Lily Allen
Princess Charlene was also confined to her home as she was taking care of her three-month-old baby daughter Princess Gabriella, who had reportedly fallen ill. Charlene's husband Prince Albert attended on his wife's behalf and was pictured arriving with his older sister Princess Caroline.
Caroline's son Andrea Casiraghi also had to miss the ball, to be at the side of his heavily pregnant wife Tatiana Santo Domingo. Boho beauty Tatiana is due to give birth to the couple's second child within the next few days, HELLO!'s sister publication HOLA! has previously reported.
Gad Elmaleh, pictured in January at the presentation of Princess Charlene's twins to Monaco, usually accompanies his girlfriend Charlotte Casiraghi to family events
While there were notable absentees from Monaco's royal family at this year's annual ball – held in support of the Princess Grace Foundation – those that did attend looked to be having the time of their life.
Charlotte, who has a baby son Raphäel with her partner Gad, was pictured tearing up the dance floor with her brother Pierre, his fiancée Beatrice Borromeo, and pop star Lily Allen who provided the entertainment for the night.
Charlotte, 28, looked as chic as ever in a sequinned pink and black dress while her future sister-in-law Beatrice dazzled in a shimmery gold gown.