The two ladies – who have been pals for years – were clearly revelling in each other's company as they opened a new museum in Leven, Belgium.
Born two years apart, and both university-educated, Maxima and Mathilde have plenty in common.
The pair – who pride themselves on being hands-on mums – were both working women with flourishing careers when they met their princes.
Argentine-born Maxima was an executive at Germany's Deutsche Bank in New York when she started dating Prince Willem-Alexander.
Meanwhile 36-year-old Mathilde was employed as a speech therapist when she met her future husband, Philippe, during a game of tennis.
The friends, who are both fluent in several languages – Maxima speaks Dutch, English and Spanish while Mathilde speaks Dutch, French, English and Italian - are also united by their shared sense of style.
Regarded as among Europe's most elegant royal consorts, they always dress to impress – and the museum inauguration was no exception.
Thirty-eight-year-old Maxima was pretty in a pink sequinned dress and long pink jacket and Mathilde was typically stylish in a grey pencil skirt and top combo.