Data released by police under the Official Information Act shows members of the public have made 235 such community roadwatch reports so far this year.
The reports are submitted online.
Last year people reported 156 incidents, and 81 were logged in 2016.
Police declined to release the number of drivers reported for using other distracting devices, including books, laptops or newspapers, citing the "substantial collation or research" required.
Meanwhile, the number of crashes in the South so far this year involving drivers distracted by their cellphones has already reached the same level as the total recorded last year.
NZ Transport Agency figures show there were 17 crashes in the year to October 11 in which "attention diverted by cellphone" was recorded as a contributing factor.
Six were in the Otago Coastal police area, seven in the Otago Lakes Central police area and four in Southland.
There were 17 such crashes in total in 2017, and 23 in 2016.
Nationally, 211 crashes were partly or wholly caused by drivers distracted by mobile phones in the year to date.
In a statement, Southern district road policing and operations manager Inspector Amelia Steel, of Dunedin, had a simple message for people who use cellphones while driving: pull over or put it away.
"Put your passengers and other road users first.
"Nobody wants to share the road with a driver who is not paying full attention.
"The research is very clear and our messaging has been consistent for years — changing these driving behaviours and attitudes are critical to reducing the deaths on our roads."
Asked why police thought more people were reporting incidents, she noted the community was "actively participating in helping keep road users safe".
