It was the flawless choice for the royal, who is six months pregnant with her third child. A Catherine Walker houndstooth topper in red and white brought a modish twist to the Duchess's maternity coat game, while underneath, Middleton took a polished tack in Sarah Burton for Alexander McQueen's bouclé shift.
The duchess, who is expecting the couple's third child, drank an alcohol-free version of the drink called glogg, which is usually mulled wine or coffee with alcohol.
The royal couple even had the chance to meet with some of the young players.
Later in the day, the Duke and Duchess met King Carl XVI Gustaf and Queen Silvia of Sweden at a luncheon, before strolling around Stortorget Square with Crown Princess Victoria and Prince Daniel.
Prince William, 35, was slightly more casual in a navy jacket and pants worn with a jumper and blue shirt, with the couple being warmly welcomed by heir to the throne Crown Princess Victoria and her husband, Crown Prince Daniel - a former personal trainer. They were escorted to the lunch by Crown Princess Victoria and Prince Daniel.
Kate Middleton may dress up more than the average civilian, but it's still a rare occasion to see her in full black-tie regalia.
Later at the Matteusskolan, a combined primary and comprehensive in the city centre, the Duke, Duchess and the Swedish royals went on a walkabout meeting dozens of children waiting to greet them outside. For dessert, they enjoyed blackberry soufflé with chocolate ganache, before a selection of British cheeses.
Apart from perhaps Alexander McQueen (it's really neck and neck), there's no other brand the 36-year-old has worn more for formal events, often choosing pieces featuring Canadian-born, British-based designer Erdem Moralioglu's trademark florals.