"Good morning" or "good afternoon," he said during three scheduled sessions that lasted all day, after which jurors filled out a questionnaire kept off-limits to the public.
Hernandez, former New England Patriot tight end, is indicted in the June 17, 2013, death of semi-pro football player Odin Lloyd, who was shot seven times, prosecutors say, in an industrial park around 3:30 in the morning.
Hernandez, Ernest Wallace and Carlos Ortiz have pleaded not guilty to the slaying.
Wallace and Ortiz will be tried separately.
Wearing a dark suit and plaid tie in the morning and switching to a pink tie in the afternoon, Hernandez kept a serious expression as he appeared to be constantly scanning the faces of men and women from whom 18 jurors, including six alternates, will be chosen. The pool includes more than 1,100 people from Bristol County, Massachusetts.
Judge Susan Garsh outlined the importance of a jury and said she believes it's a privilege to serve.
With his defense team at his side, a clerk read the three charges to the jury pool. They are murder, unlawful possession of a .45 caliber gun and unlawful possession of .22 ammunition.
Prosecutors said they have not been able to find the weapon used. It is believed to be a .45 caliber handgun.
"An indictment is just a piece of paper," Garsh told the jury pool. "It's not evidence of anything."
She told the pool Hernandez is presumed innocent and that prosecutors must prove guilt beyond a reasonable doubt.
Outside court, defense attorneys declined to answer questions as they carted in supplies, including bottled water, paper towels and a mini-refrigerator.
Acting District Attorney Thomas Quinn made a prepared statement to reporters.
"We look forward to a jury being selected that is fair and impartial to both sides. The court has gone to great lengths to ensure that this takes place," Quinn said. "We look forward to the start of the trial."
It's unclear how long it will take to seat a jury.
Individual questioning of potential jurors is not expected to begin until January 16.
On Friday, an official order granting immunity was issued for Jennifer Mercado, a relative of Hernandez.
She also is a cousin of Tanya Singleton who spent time at Singleton's home, where a dusty silver SUV was discovered by police in Singleton's garage after Hernandez's arrest.
The SUV, investigators say, is believed to be connected to a 2012 double slaying in Boston. Hernandez also has been charged in that case and has pleaded not guilty.
Prosecutors are also seeking immunity for Hernandez's fiancée and mother of his child, Shayanna Jenkins. The immunity request remains under seal.
Jenkins has pleaded not guilty to charges of lying to a grand jury.
Authorities have suggested Jenkins may have disposed of the suspected weapon used in the killing, allegedly following instructions from Hernandez.
The day after opening statements, jurors will be taken by bus to see the inside of Hernandez's home, at the request of the defense. The panel will also be shown the killing scene, about a mile from the home, and cellphone towers that allegedly captured a ping from Hernandez's phone in an industrial park the night of Odin Lloyd's death in that location.