He attended Boardman High School, where he earned Parade magazine All-American honors in 1981 as a senior and was Ohio's Division I "Player of the Year."

In the game, Kosar passed for 300 yards and two touchdowns, and the Hurricanes topped the Cornhuskers, 31–30, for Miami's first national championship.

[4] In 1984, he set Hurricane season records with 3,642 yards and 25 touchdowns, was a second-team All-American and finished fourth in Heisman Trophy voting.

[6] Earlier the same year, Kosar watched as replacement quarterback Frank Reich of the Maryland Terrapins launched what was then the biggest comeback in college football history, coming back from a first-half deficit of 31–0 to win a 42–40 victory.

Kosar graduated from the University of Miami School of Business with a double major in finance and economics.

In 1985, Kosar was a highly sought NFL prospect, described as having "an elite football IQ" and "being able to decipher a defense quicker than his coaches.

"[2] But his route from the University of Miami to the National Football League would prove to be filled with widespread controversy and the use of highly unconventional transactional and draft NFL tactics.

"[12] Teams soon learned of the Browns' highly unorthodox trade with the Bills to obtain Kosar in the supplemental draft.

Several teams asked then NFL Commissioner Pete Rozelle to prevent the unusual trade between the Browns and Bills.

Rozelle, in turn, announced that he was giving Kosar until April 23 to submit eligibility documents for either the traditional or supplemental draft.

In the divisional playoffs against the New York Jets, Kosar threw for a then-playoff-record 489 yards (a record since broken by Tom Brady in Super Bowl LII) in leading the Browns to a 23–20 comeback victory in double overtime.

But the following week, John Elway's 98-yard drive in the AFC championship game kept the Browns out of the Super Bowl.

In the strike-shortened season, he completed 62 percent of his passes for 3,033 yards and 22 touchdowns and led the AFC in quarterback rating.

In an AFC championship rematch against Elway's Denver Broncos, Kosar threw for 356 yards and three touchdowns in a 38–33 loss.

Kosar spent the final two years of his NFL career with the Miami Dolphins as backup to Dan Marino.

He hosted the Nestlé/Bernie Kosar Charity Classic at Tanglewood National Golf Club in Bainbridge Township, Ohio throughout the 1990s.

[21] In 2001, Kosar purchased the Florida Panthers, a National Hockey League team, along with pharmaceutical businessman Alan Cohen.

[31] In July 2010, it was reported that Kosar was on the verge of losing property in Geauga County, Ohio for unpaid back taxes totaling $173,557.90.

[38] As part of the product launch, Kosar partnered with Foundation Health Solutions, an Ohio-based long-term care company.

Ferre filed for divorce in 2005, alleging that Kosar had engaged in reckless spending, bad investments, and drug use.

[43] Kosar was prominently featured in Broke, a 2012 ESPN 30 For 30 documentary about the financial problems common among high-earning athletes.

[44] On September 29, 2013, Kosar was pulled over by law enforcement in Solon, Ohio for speeding and was arrested on suspicion of driving under the influence of alcohol.

He later pleaded no contest to a lesser charge of reckless operation and received a $750 fine and suspended jail sentence.

[47] Kosar continues to deal with lingering health issues related to several concussions he sustained during his playing career and enrolled in a treatment program to alleviate his symptoms.

[48] Kosar says the experimental treatment has been helpful and has promoted it to other players who may have developed symptoms related to chronic traumatic encephalopathy.