Vowing to do a better job overseeing Mayor de Blasio’s administration, the City Council last week voted to boost its operational budget by $17.2 million, to $81.3 million total.

If the cash really goes to fulfill Speaker Corey Johnson’s promise to make the council a serious check on the mayor, it’ll be money well spent.

The new funds include $13.1 million to hire 125 new staff, for 463 total, plus $4.1 million to rent new offices and other support costs, as well as $1 million for outside lawyers to work on a lawsuit seeking “property-tax equity.”

Johnson argues that the City Charter makes the council a branch of government equal to the mayor, who of course will still control vastly more staff. (Indeed, the charter gives the council the power to set its budget, with no say for the mayor.)

We’re never eager to see the public payroll balloon, and we’d be shocked if patronage didn’t play a role in the new hires.

But we’ll grant that the speaker has already done more than his predecessor, Melissa Mark-Viverito, when it comes to oversight.

Notably, Johnson and his colleagues have exposed Housing Authority deceptions as well as serious heat/hot-water problems for NYCHA tenants.

And the new jobs look targeted at making good on Johnson’s vows: Twenty spots for investigations committees, and 83 more for the Land Use, Finance and Infrastructure committees. (Another 20 jobs, on the council’s commission to propose changes to the City Charter, will be temporary.)

At the very least, this isn’t remotely as raw as the 32 percent pay hike the council voted itself in 2016 (which did need de Blasio’s OK, and got it).

The test will be whether the public gets real oversight, exposing Team de Blasio incompetence and excess. There’s certainly plenty of work to do on that front.