In an eye-popping reversal, college-readiness rates at Mayor de Blasio’s Renewal schools nearly doubled last year — but not everyone is touting a turnaround just yet.

For all 29 Renewal high schools, the average CUNY college-preparedness rate was 23.6 percent — up sharply from 12.3 percent in 2016.

Until last year’s abrupt hike, the metric had been a nagging problem for de Blasio and the DOE. While other indicators saw progress, college-readiness numbers — especially at Renewal schools — were often ugly.

Schools with soaring graduation rates were sometimes unable to muster even 10 percent college-readiness averages for their kids.

But thanks in part to eased CUNY standards, the DOE was able to present an overall 9 percent college-readiness hike after years of stagnation.

“They are potentially impressive,” said CUNY Graduate Center education professor David Bloomfield of the higher rates. “But this requires further analysis in terms of the actual numbers of students and how the numbers might be adjusted in terms of CUNY admissions requirements.”

Bloomfield cautioned that Renewal schools often have small graduating classes that are subject to wide statistical swings.

“We always want to be comparing apples to apples, so comparisons become difficult when standards keep shifting,” he said.

While acknowledging CUNY’s changing threshold, the DOE said city schools would have seen an overall 5-percent hike in the metric without the changes.

Overall college-readiness rates for Renewal high-school populations rose from 17 percent in 2015-2016 to 28 percent in the next school year, according to the DOE.

A cornerstone of de Blasio’s education platform, Renewal schools have been showered with cash and consultants in an effort to pull them from the brink of closure.

Their college-readiness renaissance outpaced the city average last year — with some schools doubling, tripling or even quadrupling their numbers, according to DOE data.

Automotive HS went from a 4-percent college-readiness rate in 2015-2016 to 23 percent the next school year, according to the figures. Fordham Leadership Academy saw its grim 6 percent 2016 rate soar to 24 percent the next, while Juan Morel HS spiked from 4 percent to 22 percent.

The Bronx HS of Business snagged the highest percentage-point increase last year, going from 15 percent in 2016 to 37 percent in 2016-2017.

Of all 29 Renewal high schools, only two saw their college-readiness rates drop last year after CUNY’s changes.