She opted primarily for British designers, with a few international names thrown in, and was also spotted wearing some of Princess Diana's notable pieces of jewellery.
For the occasion, the Princess of Wales rented her dress, a bright green off-the-shoulder gown from Solace London, and paired it with halo emerald and diamond earrings by Asprey, and an emerald and diamond choker that once belonged to Princess Diana.
Earlier that day, she'd made a solo visit to the Centre on the Developing Child at Harvard University, as part of her work emphasising the importance of the early years in childhood. For this, she wore a midi houndstooth dress by London designer Emilia Wickstead, with blue Mulberry bag, Gianvito Rossi pumps and Liv Thurlwell gold hoop earrings.
On Thursday, the Prince and Princess of Wales joined Boston Mayor Michelle Wu and the city's Chief of Environment, Energy and Open Space for a walk around Piers Park and the East Boston Waterfront. To protect herself from the chilly New England weather, she chose a brown custom wool coat from Alexander McQueen over a ribbed orange turtleneck jumper and matching midi skirt by Gabriela Hearst.
That same day, she'd visited a climate tech lab and youth charity wearing a pale pink pussy bow blouse with a burgundy trouser suit by French brand Roland Mouret, which matched Prince William's maroon jumper, along with Daniella Draper gold-and-diamond hoop earrings and burgundy suede pumps.
On arrival day, the princess stepped off the plane at Boston's Logan International Airport in a chic Alexander McQueen trouser suit with a matching turtleneck, Gianvito Rossi suede pumps and Princess Diana's diamond-and-sapphire earrings.
She later changed into a green tartan Burberry dress to meet Wu, perhaps in a nod to St Andrew's Day in Scotland, where she and her husband first met. She also wore a green coat by Alexander McQueen with a Mulberry handbag, Emmy London heels and Shyla London pearl earrings.
In the evening, for a basketball game between the Boston Celtics and Miami Heat, she chose a more casual look, with a cobalt blue double-breasted tweed vintage blazer by Chanel, with dark grey jeans and black suede pumps, once again by Gianvito Rossi. She accessorised with a Laura Lombardi chain necklace and another pair of earrings by Shyla London, hoops this time.