There was initially some confusion because once a batsman has left the field of play, they are unable to return to the crease - unless they are returning after having retired hurt. However, news.com.au understands Western Suburbs players allowed Warner to return because they did not want him to be dismissed in such a fashion.
Warner went on to raise his bat for a half-century, reaching 50 as Randwick-Petersham moved to 93-2.
The walk-off came after Warner's blazing return to club cricket in September.
Playing at Coogee Oval for Randwick-Petersham, Warner smashed a century and capped it off with a trademark celebration, leaping into the air and waving his bat.
The crowd, which had been building from a smattering from early in the day, gave Warner a great reception as he moved into triple figures.
Former Aussie skipper Steve Smith is also having a field day with the bat back home, drawing huge crowds of faithful fans as he takes the field for Sutherland.
In his first game back on Australian soil since the ball-tampering scandal exploded in South Africa in March, Smith received a warm welcome from the crowd, with the spectators applauding every run the former Aussie skipper scored.
It was Smith's first grade cricket outing since 2013.
Two reviews prompted by the ball tampering incident - one focusing on the culture within Cricket Australia and the other into the team - are due to be released on Monday.