Figures obtained by the Evening Times show that the authority made £2,469,420 from fines issued to drivers wrongly using the city's 16 camera-enforced bus lanes last year.
The council has previously said the money goes towards administering and collecting fines.
But our investigation found that the cost of sending out and collecting penalties totalled just £437,453 - leaving a profit of more than £2m - £2,031,967.
A spokesman said the surplus is invested in local transport strategies.
Today is the first of a series of features in which we look at the effectiveness of bus lanes across the city.
Opinion remains divided, with the council assuring the public they are vital for improving the reliability of public transport but motorists have argued that they are a "cash cow".
Figures released to the Evening Times, under the Freedom of Information Act, show that the most profitable bus lane camera is on Glassford Street, where 23,250 motorists were caught in 2013, netting £545,280 for the council.
We told you last year how the same camera, which is near an entrance to a NCP car park, pulled in £700,000 after 28,000 drivers were fined for illegally driving in the lane from April to December 2012.
Motorists have previously hit out at the signage surrounding the camera, with some claiming it is misleading.
But Glasgow City Council hit back, stating that the vast majority of drivers will never receive fines because they stay within the law.
Our figures show that the lane which caught the second highest number of drivers was in Hope Street - 11,381 drivers were snapped generating a total of £290,130 in fines - followed by Argyle Street, at Jamaica Street, where £191,400 was gathered from 11,279 drivers.
Closely behind was Victoria Road, where 11,032 drivers were snapped, generating £289,350 in fines.
In fifth place was Maryhill Road, at Bisland Drive, where £285,060 was gathered from 10,609 drivers.
This was closely followed by West George Street, where a camera caught 10,431 drivers wrongly using the lane, netting £262,800 in fines.
There are a total of 173 bus lanes of varying lengths across Glasgow but, of these, only 15 are regulated by cameras which produce automatic fines for cars caught in them. The £60 fine is reduced to £30 if paid within 14 days.
A 16th camera, on Cathedral Street, was removed in March last year after a section of the road was closed to traffic.
Some of the camera-enforced lanes restrict use 24 hours a day, seven days a week and in others cars are only banned during peak times - Monday to Saturday between 7am and 9.30am and 4pm and 6.30pm.
A spokesman for Glasgow City Council said: "Money from bus lane penalty charge notices is invested in transport strategies.
"These are a balanced strategy concentrating on promoting and enhancing sustainable transport options. These include walking, cycling, public transport, investment in roads through tackling key congestion points, essential links to development areas and links to enable public transport to provide effective services."