Mayor Bill de Blasio kept the Big Apple in the dark during Saturday’s blackout by not communicating enough with city residents amid the confusion, City Council Speaker Corey Johnson said Tuesday.

“One of the things that should’ve happened right away is there should’ve been communications from the mayor’s office in a similar way that other elected officials were doing because that’s not the hardest thing,” Johnson told Fox 5’s “Good Day New York” on Tuesday, referring to the absentee mayor campaigning for president in Iowa when a large swath of Manhattan went dark over the weekend.

“That’s a really important thing,” he said.

Johnson — who is running for mayor in 2021 and said he did not personally communicate with de Blasio during the blackout — was widely praised for keeping New Yorkers calm amid the darkness.

Johnson, too, was out of town on Long Island when the lights when out — but that didn’t stop him from doing his best to update New Yorkers while heading back to the Big Apple.

“I wasn’t in the city; I had just gotten to Long Island, but I got on the phone and I was tweeting updates as quickly as I could,” he said. “I was on the phone with the MTA. I was on the phone with Con [Edison]. I was on the phone with [the Office of Emergency Management].”

De Blasio tweeted 15 times throughout the blackout, with 11 of the posts being retweets of city agencies or himself. The first missive came at 8:22 p.m. — about two hours after the power failed.

Host Rosanna Scotto repeatedly asked about de Blasio’s sagging presidential campaign, but Johnson wouldn’t say whether Hizzoner should drop out of the race and concentrate on New York.

He did, however, acknowledge that de Blasio faces a tough road ahead.

“Running for president and being mayor of New York City is a very difficult balance because at any moment in time, something like this could happen,” he said.