The Canada-born royal strolled hand-in-hand with her husband Peter Phillips as they joined the rest of the British royal family returning from their ten-day Scottish cruise.
It was the first time the couple had been photographed in public since announcing the happy news they will welcome their first child.
Autumn and Peter were with the Queen, Princesses Beatrice and Eugenie and Princess Anne among others as the party disembarked from the Hebridean Princess at Scrabster in Caithness.
Making a rare public appearance were also the Earl and Countess of Wessex and their children Lady Louise Windsor and James Viscount Severn.
Prince Charles was unable to go on the trip, which was chartered by the Queen and the Duke of Edinburgh to celebrate Princess Anne's 60th birthday on August 15 and the Duke of York's 50th, which fell in February.
Instead, Charles met the party and accompanied them to the nearby Castle of Mey, home of the late Queen Mother, where he hosted a luncheon.