Election rules prevented them from running the ads in the past two weeks, but the blackout period ended at midnight.
The Liberals are rolling out a TV commercial across the province, as well as 35 different radio spots voiced by Premier Kathleen Wynne.
The commercial shows Wynne talking about her platform, but also slamming Tory Leader Tim Hudak's plans to cut 100,000 jobs in the public sector.
Party officials say the commercial isn't a negative ad, but one that shows the choice voters face in the June 12 election.
The Tories are also putting out a radio ad targeting the Liberals and their costly decision to cancel two gas plants ahead of the last election at a cost of up to $1.1 billion.
However, their TV commercial is focused on Hudak talking about his plan to create an additional half million jobs over the next eight years to employ more people looking for work.
Meanwhile, the NDP are expected to have a "wrap" — a cover page — of one the large daily newspapers whose readership isn't typically associated with their voters.
Party strategists say they're targeting undecided voters, particularly those who have voted Conservative in the past but don't like Hudak or his policies.
Today is Wynne's 61st birthday and she'll be making campaign stops in Oldcastle, Cambridge and Thornhill.
Hudak is heading east of Toronto with visits to Cobourg and Peterborough, while Horwath is in Brampton and Toronto.