The 17-year-old Young Matildas midfielder lashed in a fierce right-footed shot from the edge of the penalty area in the 34th minute of the second leg encounter at ctrl:cyber Pitch on Saturday..
Minor premiers City will play the winner of Sunday's other semi-final between Wellington and Brisbane at Melbourne's AAMI Park next Saturday.
The Roar carry a 2-1 lead over from the first leg at home into the second leg at Porirua Park.
The Victory, who finished sixth on the ladder, had 56 per cent possession and five more shots, but City goalkeeper Malena Mieres made several saves.
"They hit the crossbar at the end and a couple of dangerous crosses and shots, but overall I thought we managed the game well," City coach Michael Matricciani told Paramount Plus and Network Ten.
"Our game plan worked and we created our four or five chances as well.
"When Shelby puts that sort of goal away its a special moment."
Victory coach Jeff Hopkins said he was extremely proud of how this team played.
"There were moments there when the game and things might have been a little bit different, but every credit to City, they stuck with it, they defended really well," he stated.
"For a big part of the first half and a big part of the second half we took the game to City and had a real good go.
"The way that we went about things and the way that we attacked, our tactical plan was great.
"Probably in the real key moments of the game we were just wanting a little bit."
