The Public Sector and MPP Accountability and Transparency Act passed Tuesday on third reading in the legislature.
The bill was revived after dying with the June election call, and follows the gas plants scandal which saw the Liberal government accused of wiping hard drives — sparking a police investigation.
The legislation makes it an offence to alter, conceal or destroy records with intent to deny an access request, with a penalty of up to $5,000.
Under the law, cabinet ministers, parliamentary assistants, opposition leaders and their staff are required to post expenses online.
It will also give the government the ability to control the pay and benefits for executives in the so-called broader public sector, such as Ornge, eHealth, Metrolinx, OLG and the LCBO.
In addition, it will allow the Ontario ombudsman's office to investigate complaints about municipalities, universities and school boards for the first time.
Ontario Ombudsman Andre Marin quickly welcomed the passage of the law, saying the province had taken a big step forward in ensuring accountability in the broader public sector.
Deb Matthews, president of the Treasury Board, called the bill "a signature piece of legislation" that sets a high standard for oversight across the public sector.
"It is part of Ontario's commitment to be the most open and transparent government in the country."