David Duckenfield was the match-day commander at the FA Cup semi-final between Liverpool and Nottingham Forest at Sheffield Wednesday's Hillsborough ground on April 15, 1989.
Duckenfield, 74, has pleaded not guilty to 95 counts of gross negligence manslaughter following the fatal crush in the Leppings Lane end.
The trial is taking place at Preston Crown Court in northwest England. The city is 25 miles (40 kilometres) from Liverpool.
There is no manslaughter charge over the death of a 96th casualty, Anthony Bland, as he died almost four years later, and under the law in 1989 his death is now "out of time" to be prosecuted.
Duckenfield sat next to co-defendant, former Sheffield Wednesday club secretary Graham Mackrell, who is charged with an offence involving the stadium safety certificate and a health and safety offence.
The trial began with the whittling down of 100 potential jurors to the final panel of 12, with candidates asked if they supported any of the clubs involved or knew either of the men on trial.
It is unknown how long the trial is expected to last.
Families of the Hillsborough victims fought a long campaign for events surrounding the disaster to be re-investigated, and around a dozen family members were in court for the start of proceedings.
The Crown Prosecution Service, England's state prosecutors, announced the decision to press charges in June 2017.
"We will allege that David Duckenfield's failures to discharge his personal responsibility were extraordinarily bad and contributed substantially to the deaths," the CPS said at the time.
Former police officers Donald Denton and Alan Foster, plus retired lawyer Peter Metcalf, will go on trial in September, charged with doing acts intended to pervert the course of justice.
The crush was Britain's worst sports stadium tragedy.
The final memorial at Liverpool's Anfield stadium for the 96 victims was held in 2016, 27 years to the day since the disaster took place.
Families of the deceased unanimously agreed the service would be the last public event at Anfield in memory of the supporters who died.