There were 112,832 loans in 2014/15 compared to 207,619 in 2011/12, a 46% fall.
Opening hours reduced at seven of the libraries after volunteers took over, but total hours rose 6.8%.
The county council said volunteers deserved credit for ensuring services remained.
When the library service lost nearly a third of its budget, the 12 would have closed without community support, the authority said.
Kineton, which became community-run in January 2012, had 6,543 loans in 2014/15 compared to 8,754 in 2011/12, a fall of 25%.
But its weekly opening hours reduced from 13.5 to nine and the latest figure is a 4.7% increase on the volunteers' first full year in charge, 2012/13.
Dordon, Hartshill and Studley were the other libraries with increased loans over that time up to 2014/15, but across Warwickshire there has been a 10% fall since 2012/13.
Friends of Kineton Library chairman Michael Harris, 72, said comparisons were difficult due to reduced opening hours and the library had maintained 20 volunteers.
Mr Harris said: "One of the main reasons I felt [saving the library] was important... was to provide a point in the village where people could come and talk as well as actually borrow books."
Kineton library user Kathryn Gandy, 46, said her two girls aged nine and five "love coming".
She said: "There is still such a good, wide range for them to choose from and especially with my eldest daughter... if she needs to have a book with a particular reference towards something for a project, then they nearly always have it."
The council said the libraries had responded to "specific needs", with some incorporating cafes, shops and even a dance school.
The number of loans has gone down at all 12 of Warwickshire's community libraries since they were formed following council cuts.