The royal couple spoke to members of the cathedral choir after the service The Duke and Duchess of Cambridge have marked Easter Sunday by attending a church service in Sydney.
William and Catherine were greeted by cheering crowds outside St Andrew's Cathedral in the city centre.
While at the cathedral, they signed the First Fleet Bible, which was brought to Australia in 1788 and bears the names of other members of the royal family.
The couple then moved onto Taronga Zoo, where Prince George was introduced to a bilby, a rabbit-like marsupial.
Prince George was introduced to a bilby on the zoo tour
The bilby enclosure was built to celebrate Prince George's birth 
The couple met Leuca the koala 
William and Catherine watched a bird display Bilbies, which hide in burrows during the day and have large ears to pick up the sounds of insects and long noses to sniff out seeds and bulbs, were once common in Australia.
But there are now only 10,000 left in the wild because of the threat from non-native species like foxes and cats.
Dressed in a blue striped shirt, blue shorts and black shoes, the young prince looked excited to meet the native animal, which was named George in his honour.
He was handed a toy version, throwing the gift to one side.
William and Catherine also unveiled a plaque at the bilby enclosure, which was paid for by the Australian government to celebrate George's birth.
Prayer bookEarlier, the private church service was also attended by Australian prime minister Tony Abbott.
Archbishop of Sydney the Most Reverend Dr Glenn Davies and Dean of Sydney the Very Reverend Phillip Jensen met William and Catherine on the cathedral steps before the service began.
The bible had previously been signed by the Queen and Duke of Edinburgh as well as the Prince of Wales and Diana, Princess of Wales in 1983 on their visit to Australia with an infant William.
William and Catherine also signed the prayer book of the First Fleet - the 11 ships that carried Europeans to Australia in the 1780s.
The Archbishop of Sydney and Dean of Sydney met William and Catherine outside the cathedral 
Huge crowds were in Sydney to see the couple 
William and Catherine both signed the First Fleet Bible 
Several members of the royal family have previously signed the bible 
Catherine spent time talking to other children who had gathered outside Catherine wore a dove grey Alexander McQueen coat and Jane Taylor hat for the service, while her husband wore a suit.
After the service, they spent time speaking to members of the cathedral choir and children who had gathered nearby to see the royal couple.
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