Péladeau was appointed President of Quebecor Communications Inc. in 1991. This division included the company's main publishing assets and some distribution and Retail operations.

In 1994, Péladeau relocated to Paris to help his company's growth. As President of Quebecor Printing Europe he developed the new subsidiary through a series of acquisitions in France, the United Kingdom and Spain, building it into Europe's largest printer.

In 1997, after the sudden death of his Father, he returned to the Montreal head office to assume the position of executive vice President and chief operating officer of Quebecor Printing Inc. with overall responsibility for the company's worldwide operations.

In 1998, Péladeau spearheaded the acquisition of Sun Media Corporation, making Quebecor the second largest newspaper chain in Canada.

In 1999, he carried out the acquisition of World Color Press by Quebecor Printing Inc. The acquisition created Quebecor World Inc., one of the world's largest printers. Quebecor World had, at one time, operations in 17 countries on three continents and employs approximately 35,000 employees. In 1999 the board of Directors of Quebecor Inc. named him President and CEO of the company.

He also has another child, Marie (born 2000), who was born of his previous union with Isabelle Hervet, a native of France.

In 2008, Quebecor World went bankrupt as the printing Business collapsed. He allegedly resents the failure from the Royal Bank of Canada and the English Canadian Business establishment to refinance.

Quebec Liberal leader and Leader of the Opposition Philippe Couillard, as did Coalition Avenir Quebec leader François Legault, felt that if the PQ won another term, it would be a severe conflict of interest for the owner of half the media outlets in Quebec to be a government backbencher. Comparisons between Peladeau and Silvio Berlusconi have been seen. Peladeau had in 2010 refused to meet with John Gomery, President of the Conseil de presse du Quebec, over his withdrawal from the Conseil of two of Quebecor's newspapers, the Journal de Montréal and the Journal de Québec.

On 15 May 2013, Péladeau was appointed by Pauline Marois to be chairman of the board of Directors of Hydro-Québec, which is the largest hydroelectric Producer and distributor in Canada. He resigned in March 2014 to pursue his political ambitions.

Péladeau was narrowly elected with 37 percent of the vote. His first day at the National Assembly was on 26 May 2014, eight days after a bike accident in the Eastern Townships left him with four fractures.

Recently divorced, his new girlfriend is Lucie Laurier (Canadian actress). He was in a long-term relationship with Julie Snyder, which produced two children, Thomas (born 2005) and Romy (born 2009). Their separation was announced in December 2013, but the couple later reconciled and were married on 15 August 2015 in Quebec City, Quebec. They separated again in January 2016, less than five months after their marriage.

His girlfriend Marie-Christine Couture was discovered dead in October 2016 at her home in Montreal. Police theorize it was from suicide.

Péladeau returned as Quebecor's CEO and President on February 16, 2017, with Brian Mulroney remaining as chairman.

Péladeau joined his father’s management team at an early age. He is known to be confrontational with unions and has used lock-out tactics at least 14 times. He counts Brian Mulroney amongst his Business associates. Péladeau sits on the boards of several Quebecor companies and is active in many charitable and cultural organizations. Quebecers identify him with his initials, PKP.