Guests such as designers Prabal Gurung and Oscar de la Renta and photographer Mario Testino posted photos on Instagram using the hashtag #ThisMasticMoment.
Shaffer, 28, tied the knot with fashion exec Elizabeth Cordry, 27, in Mastic, New York, in a spectacular garden-themed bash.
Wintour, 64, wore Chanel, the bride wore a custom Oscar de la Renta, the groom wore Burberry, the flower girls wore Alexander McQueen.
And the bridesmaids? Prada, naturally.