Katz is married to Renee Gouin. She is the daughter of Jean Yvon (Ivan) Gouin. In 1952, her Father founded the North American Construction Group which became one of the largest mining and heavy construction companies in Canada.

Daryl Katz was born in 1961 in Edmonton, Alberta. His Father was a pharmacist who founded Value Drug Mart in Edmonton in the 1970s. Katz attended the Jewish day school, Talmud Torah School during his elementary years and then graduated from Jasper Place High School. He then attended the University of Alberta, graduating with an arts degree in 1982 and with a law degree in 1985.

After school, he worked for a time at the law firm, Shoctor, Mousseau and Starkman, and then started his own practice focusing on corporate and franchise law. In 1991, in a partnership with his Father, Katz paid $300,000 for the Canadian rights to the U.S.-based Medicine Shoppe drugstore franchise which had over 1,000 stores in the USA. In 1992, they opened the first Medicine Shoppe store and Katz founded the Katz Group of Companies which was to become the holding company for the group. In 1996, Katz purchased the storied but fading Rexall drugstore chain in Canada which at the time, only consisted of several dozen stores. The Business grew and by 1998, the Katz Group consisted of 80 Rexall stores, 30 Medicine Shoppe outlets, and a few smaller independent Retailers. In 1997, he purchased the Ontario-based, 143-store Pharma Plus drug store chain from the supermarket operator Oshawa Group for $100 million.

In 1999 he ventured into the U.S. with the purchase of the money-losing, $300 million in sales, Minnesota-based Snyders Drug Store chain; in 2001, he purchased the U.S.-based Drug Emporium big-box discount chain. His foray into the U.S. was not without failure: the Snyder's chain filed for bankruptcy in 2003 and its 25 stores were sold to Walgreens. In 2004, Katz purchased the naming rights for ten years to the new $45-million Rexall Centre, a 12,500-seat tennis and entertainment complex on the campus of York University. In January 2012, he sold Drug Trading Co. and Medicine Shoppe Canada to the U.S.-based drug distributor McKesson Corporation for $1.2 billion. Katz Group retained its network of approximately 460 corporate-owned 450 Rexall-branded outlets.

Between 2005 and 2010, Katz and his wife have donated "over $50 million" to organizations and institutions across Canada.

In October 2006 Katz announced a $7 million donation to the University of Alberta Faculty of Pharmacy and Pharmaceutical Sciences and Faculty of Law. Matched by the province, the gift was the largest donation ever to a Canadian pharmacy school. The west wing of the Health Research Innovation Facility at the corner of 87th Avenue and 114th Street in Edmonton has been named The Katz Group Centre for Pharmacy and Health Research. In 2009 Katz donated $20 Million to Mount Sinai Hospital in Toronto and founded The Daryl A Katz Centre For Urgent And Critical Care. Katz has also given "millions" to the Stollery Children's Hospital in Edmonton, as well as supporting public events.

In July 2007, he made another bid for the Oilers of $185-million, which was turned down by the Edmonton Investment Group (EIG) on August 7, 2007. On December 12, 2007, Katz made an offer of $188-million to the EIG. The Board of the EIG announced in January 2008 that it would again recommend to its shareholders to reject this latest bid.

On January 28, 2008, Katz increased his offer to $200 million and extended the acceptance deadline to February 5, 2008, at which time Katz was notified by the EIG that all its members agreed to sell the Oilers to him, pending league and financial approval. On June 18, 2008, Daryl Katz received the final OK from the National Hockey League to purchase the Edmonton Oilers, and then on July 2, 2008, he was officially announced as the owner of the Edmonton Oilers during a Press Conference at Rexall Place, where he was presented with an Edmonton Oilers Jersey with the number "08" and his last name patched onto the back.

Katz' net worth is reported at US$3.5 billion which makes him the 12th wealthiest person in Canada.

In June 2014, Katz Group announced that Bob Nicholson would join the organization as Vice-Chairman of Oilers Entertainment Group (OEG), a new Sports and entertainment company that would manage the Katz Group’s growing family of Sports and entertainment assets, and operate Rogers Place, the new home of the Edmonton Oilers.

The Edmonton Arena District was formally renamed Ice District on July 13, 2015.

Model and Actress Greice Santo accused Katz in 2016 of repeatedly offering her money in exchange for sex, which she refused. She alleges Katz offered to be her "fairy godfather."

With Rogers Place at its core, Katz Group has begun construction of the Edmonton Arena District (EAD), slated to be Canada’s largest mixed-use Sports and entertainment development. The EAD will cover 25 contiguous acres of downtown Edmonton, and feature a 50,000 square foot public plaza, two office towers, a JW Marriott Hotel, a Gateway casino, a Cineplex movie theatre complex, over 1,000 luxury condos and rental apartments, and 270,000 square feet of Retail space at a total cost of approximately $2.5 billion. In 2014, it was announced that the City of Edmonton and Stantec would be the major tenants of the two respective office towers. Stantec tower will be the tallest in Edmonton (62 storeys).