The city will receive a full year of funding, $2.4 million, for fiscal year 2011-12, and those funds will then escalate at 3.3% annually.
Calling the agreement a "great step forward," Councilwoman Beth Krom lauded Mayor Sukee Kang and city staff at Tuesday's council meeting.
"The spectrum, not unlike the [Irvine Business Complex], is a great example of an integrated business community where we have business and housing together and now we will have transportation to compliment that," Krom said.
Launched in 2008, the iShuttle has come under fire for what critics call low ridership numbers and a waste of public funds. However, city officials have maintained that the transit system has potential to make the city less reliant on cars and more eco-friendly.
The bus service logged 7,431 boardings in September and 7,537 boardings in October, according to the city.
Casting the lone dissenting vote, Councilwoman Christina Shea expressed doubts that the funds would be enough to cover the expansion of a route to the Irvine Spectrum, anticipated to open sometime next year.
"It really doesn't pencil out to me," she said.
The project was funded with a complicated exchange of funds.
About $121.3 million from Proposition 116 transportation bond money was transferred from the city to the county, according to Orange County Register archives, and the city was to receive the same amount back through Measure M's half-cent sales tax funds.