Avila will be joined by Councilwoman Debra Porada, who won her re-election bid last week. They will be joined by members Jim Bowman and Alan Wapner as well as Mayor Paul Leon.
Avila's election to the council comes at a critical time as the city has started negotiations with the city of Los Angeles to regain control of the L.A./Ontario International Aiport.
Avila is expected to be installed on the council in early December.
"The voters have spoken, they'd like to see Avila in a leadership role ... I look forward to working with him in the future and the opportunity to talk to him and help him with the transition," Mayor Paul Leon said.
Avila, who did not return calls for comment, has been clouded by controversy in recent years.
In 2008, he was investigated for several incidents involving him and school district employees that were deemed by an investigator as inappropriate behavior.
At one point, the board even considered censuring him.
Councilman Jim Bowman and Leon said they are willing to extend their friendship to Avila and assist him during the transition period.
Leon said he already reached out to Avila after election night to congratulate him and offer any assistance. The call was not immediately returned.
This will be the first time Leon will work with Avila and the mayor said he would like to come to his own conclusions about Avila's personality.
"I haven't seen any evidence of perceived poor behavior for a couple of years," Leon said.
Bowman said he does not want to revisit past issues.
"We have no issues except the issues before us," he said. "I don't look in the rear-view mirror, I look to what's in front of us - address the important business of the city and work together for the benefit of the city."
Wapner and Porada have worked with Avila in the past on the school board.
Since the election, Porada said she has been in contact with Avila via email.
"I believe Paul has the best interest of the city," said Porada, who described her exchange of emails with Avila as positive.
"All of us want the best for Ontario."
Wapner said he called and congratulated Avila.
Like Porada, Wapner said the focus of the council is to make sure they bring in more businesses and jobs to the city. It's also important for residents and the business community to see the council remains committed to that same direction.
"I think he's 100 percent supportive of the direction we're going," Wapner added.
Avila's bid for a seat on the council is nothing new. He has made a run numerous times and in recent years has been coming increasingly close to being voted in.
Leon says he recalls running against Avila when he first ran for mayor.
Avila and Porada jumped out to an early lead when the initial results were released on election night.
At one point, less than 650 votes separated Avila and Mautz. As the votes, counted by the San Bernardino County Registrar of Voters, trickled in through the night, Avila's lead widened over the incumbent by more than 1,200 votes. Mautz, who has been on the council for eight years, ended up in fourth place.
Despite the large pool of candidates, the race for two open seats had been a quiet one.
In her first shot on the council, Porada also unseated an incumbent. This time she was the top-vote getter in the race.
"I was surprised I won the last time," she said. "You never know what the electoral is going to do. About five to 10 percent pay attention to what happens in local politics."
Besides the airport issues, Porada said her focus will be on reinvigorating the downtown.
"I'm hoping on gaining some traction in downtown and maybe get a coffee shop soon," she said.
Bowman said he was sad to see Mautz go.
"We need to recognize the contributions Shelia Mautz made to the city of Ontario. They were significant and vast contributions, and she will be greatly missed," he said.
"I hope we can weave her back into the framework of city business, she has contributions and so much that she has still to give," Bowman said.