The NSW Government has caved to Parliament's demands to release documents about some of its most controversial policies to save its Upper House leader Don Harwin from being suspended from the chamber.

Last night the Upper House censured Mr Harwin over the Government's refusal to hand over a damning report into out-of-home care, as well as key documents about its stadiums policy and the plan to move the Powerhouse Museum to Parramatta.

Government backbencher Matthew Mason-Cox crossed the floor to support the censure motion, which gave Mr Harwin until this morning to produce the documents or give an explanation to Parliament.

If he did not, he risked being found in contempt of Parliament and suspended from the chamber.

The last time the move was used successfully was in 1999 against former Labor Treasurer Michael Egan, who ended up being escorted out of the building by the Usher of the Black Rod.

Mr Harwin surprised many in the Upper House this morning when he stood up and said the Government would deliver the documents requested by 5:00pm Friday.

It had previously resisted all formal demands from the Upper House to produce the papers, arguing they were cabinet in confidence.

Labor's Upper House leader Adam Searle said it was the first time a NSW Coalition Government leader had been censured.

"This is historic and is about the integrity of the Legislative Council to hold the Government to account," Mr Searle said.

He accused the Berejiklian Government of acting under a "cloak of secrecy" and said the Government's backflip on the documents was a "win for democracy".