San Francisco 49ers linebacker
The 24-year-old Smith entered his pleas in a Santa Clara County Superior Courtroom in San Jose. He faces a sentence ranging from spending no time in custody to a maximum of four years and four months behind bars at a judge's discretion, prosecutors said.
Smith is scheduled to be sentenced on July 25 — two days after the 49ers are to open training camp.
In November, Smith pleaded not guilty to three felony counts of illegal possession of an assault weapon after deputies said they found three assault rifles while responding to a complaint about a party in June 2012 at Smith's home. During the party, Smith fired a handgun in the air and was stabbed as two other people were shot during a melee, authorities said.
The DUI charges were filed after Smith's car smashed into a tree in San Jose in September as police said his blood-alcohol level was twice the legal limit.
"We are aware that Aldon entered a plea today in a case that we have closely monitored," 49ers General Manager Trent Baalke said in a statement Wednesday. "Today was an important step towards bringing that situation to a resolution."