Ms Evangel will be disqualified from sitting on council after she is officially sworn in as a Member of Parliament.
City of Perth chief executive Gary Stevenson said the council would decide whether to fill the vacancy once she leaves.
He said officers would recommend against holding a by-election before council elections in October.
Ms Evangel won the seat with a 10.3 per cent swing towards the Liberal Party.
Labor MLA John Hyde had held the seat since 2001.
Ms Evangel said her win showed electors wanted Perth to become a vibrant capital city and supported the Liberal Party projects.
‘Every time something new and different is proposed, people look at all the negatives that might happen,’ she said.
‘But when push comes to shove, that’s when people realise they don’t want to lose these major infrastructure projects and we do need this as a capital city.’
Ms Evangel said while she would continue to support major projects, her focus would be on improving education infrastructure in the electorate, including honouring a $1.25 million commitment towards Mount Hawthorn Primary School.
The 47-year-old businesswoman and mother of three has sat as a City of Perth councillor since 2005.
Mr Hyde said population changes in the electorate meant more Liberal voters were living in the area.
‘I was fully aware 14 months ago that population changes meant Perth was now a 10 per cent Liberal seat,’ he said.
‘While long-term residents in the CBD and new East Perth stuck with me, the big demographic influx into the new apartments went to the Liberals.’
Mt Lawley MLA Michael Sutherland was re-elected over Labor candidate Bob Kucera, with an 8 per cent swing to the Liberal Party.
Mr Sutherland said the win showed people in the area were positive about the future.
Mr Kucera said he was concerned what the election result meant for the party.
‘Obviously, I’m disappointed with the way that it went, but I’m more disappointed for the party than I am for myself because it’s about the politics, not about the individual,’ he said.