The Duchess of Cambridge, 32, looked polished in an dove grey Alexander McQueen coat with a matching Jane Taylor hat. Her proud husband stood by her side in a black suit with a pink tie.
Middleton and William sat at the front of the cathedral amongst a congregation of around 800. The mother of 8-month-old Prince George complimented members of the clergy on their "lovely" service.
"It was absolutely beautiful," she told them.
After the service, the royal couple had the honor of signing the First Fleet King James Bible, which was brought over on the First Fleet in 1788. William's mother, the late Princess Diana, signed the Bible in 1983, along with his father Prince Charles, and Middleton and William signed their names underneath. Queen Elizabeth and Prince Phillip have also signed the Bible.
William joked that the Bible was "in good nick" (British slang for good condition), and appeared moved to see so many of his family members had signed their names.
"I am sure the prince was very well briefed, but he seemed surprised that so many members of his family had signed the Bible," Rev. Moffatt said. "He seemed genuinely touched to see so many of their signatures there."
Moffatt also showed the couple the signatures of the first Christians to marry in Australia.
"I explained to him that the first convicts to settle here held those pens. The prince seems fascinated," he continued.
Middleton also spoke with several members of the choir, complimenting the youngest member, Freddie Cobb, 6, saying, "I had my eye on you right through the service. You were wonderful!"
Later in the day, the proud parents changed and took their son Prince George to the Taronga Zoo in Sydney, where he was delighted to meet his namesake bibly. ?