The program will bring in more than $10 million by the end of 2018, up from $8.3 million last year, officials said.
McHenry held an average of 233 inmates daily in the 2017 fiscal year, up from 167 in 2015, according to figures obtained by Detention Watch Network, a Washington D.C.-based group that advocates against immigration detention.
The jail's daily average population through Oct. 1 was 270 people, according to ICE figures.
Carlos Acosta, who was recently elected to the county board, questioned whether the county wants to be involved in such a partnership even as President Donald Trump focuses on stopping illegal immigration.
The county also makes additional money for transporting detainees, said Lt. Mike Lukas of the McHenry County Sheriff's Office.