The Sydney Harbour Bridge was lit up by a white light to symbolise peace, and a Jewish menorah was projected on to the pylons of the bridge to show solidarity with the Jewish community.
Official New Year’s Eve parties were paused at 23:00 local time (12:00 GMT) for a minute’s silence to commemorate the victims of the attack.
Pictures from Sydney Harbour – where thousands gather every year to watch the famous fireworks display – showed officers patrolling the crowds with longarm weapons.
In the lead up to the event, Premier Chris Minns had warned that some people may find the sight “confronting”, with police “carrying firearms and weapons that you haven’t seen before”.
“But I don’t make any apology for that. We want people to be safe in our community,” he added.
British tourists Joe and Lucy said the increased police presence reassured them.
The pair – who timed their Australia trip to coincide with the fireworks – were in Melbourne when the shooting occurred.
“We had our worries about coming for New Year’s Eve,” Joe told the BBC, adding, “but we were reading more recently in the news… how more police were going to be here, it would be a bit safer”.