The last remaining inmates at the jail in southwest Phoenix were moved to an indoor jail nearby, the Arizona Republic reported.
Sheriff Paul Penzone, who defeated Arpaio in an election last year, announced the closing of the facility in April and called it a "circus" that doesn't deter crime.
"This is another step in the stabilization of this office and its operations," Penzone said Monday. "My focus is to find more effective ways to reduce recidivism while creating a safe environment for our employees."
Penzone said the facility could potentially be turned into a no-kill animal shelter.
Tent City, a 7-acre outdoor jail where inmates lived in tents surrounded by barbwire fences, was first constructed in 1993 as part of an initiative spearheaded by Arpaio to save the county money on brick-and-mortar facilities to imprison inmates. However, closing the outdoor jail will save Maricopa County taxpayers more than $4 million per year.
Tent City was often criticized for being an inhumane facility. One of the principal complaints was that, being outdoors in Arizona's sweltering summers, temperatures at the facility would surpass 120 degrees. The facility was also a county jail, meaning many of its inmates -- including undocumented migrants detained on immigration charges -- had not yet been convicted of a crime, but were awaiting trial.
"The outdoor jail is a cruel site of torture the former Sheriff called his own 'concentration camp,'" said Carlos Garcia, the director of Puente Arizona, an immigrants rights group. "Today we have survivors of Tent City to thank for blowing the whistle on all the abuses of the Sheriff's Office."