More than 150 people attended the meeting at St Margaret's Church in Tollcross last night, to voice their opposition to the cancellation of the No64 service.
The meeting was called by Glasgow East MP Margaret Curran, and supported by local councillor Frank McAveety and Bailie Anne Simpson.
First Bus wants to axe the service, which runs from the city centre through Bridgeton and Parkhead to Carmyle.
Ms Curran said: "The large turnout shows the depth of feeling surrounding this issue.
"Buses are the most common form of public transport in the East End but too often the people who rely on them are being let down.
"People are already suffering the effect of increased prices.
"We are pulling together an action plan which will ensure that First Bus know the strength of feeling."
Bus passengers said the service provides residents in some of the most deprived areas of the city, with access to community services.
Anne Forbes, 61, of Tollcross, said: "Without the 64, I would have to get two buses to get into town and to get to the shops.
"If the 64 was cancelled, it really would cut a lot of people off.
"A lot of people, especially older folk in the area, rely on the 64 to go about their day-to-day lives."
Earlier this month, the Evening Times told how around 200 people packed a meeting about the proposals at Carmyle Community Centre.
Ms Curran added: "We need to halt the decline in services and guarantee a decent, regular and affordable service for commuters not currently being served by bus companies."
FirstGroup "initially requested the cancellation" because it says the No64 route runs at a substantial loss.
A spokesman for First Glasgow said: "There are no immediate plans to withdraw the service.
"The Competition Commission is currently reviewing plans and once that process is complete we intend to launch a consultation with our customers and other stakeholders."