The lanes were controversially introduced in 2015.
In December the Belfast Telegraph revealed that more than 40,000 penalties had been issued to drivers caught in the lanes.
With a £45 minimum fine, they total at least £5.3m.
Responding to a question from DUP MLA Christopher Stalford, Infrastructure Minister Nichola Mallon revealed her department had spent £36m installing cycling and bus lanes in Belfast since 2015.
Investment in bus lanes totalled £31.43m and includes improvements on the Belfast Rapid Transit corridors, such as carriageway widening and resurfacing, improved drainage and street lighting and installing the lines and signs required.
Meanwhile, the amount spent on the provision of cycling infrastructure in Belfast since 2015 was £4.6m.