Agent Jason Rosenhaus told The Associated Press on Tuesday that Gore had agreed to terms on a new three-year contract extension that keeps him with the team through 2014.
Gore is set to make $21 million, with $13.5 million in guaranteed money.
The team hadn't made a formal announcement. That likely will come Wednesday ahead of the Niners' exhibition finale Thursday night at San Diego.
Gore said earlier Tuesday that his primary agent, Drew Rosenhaus, had a productive, all-day meeting with team brass Monday. Gore said he instructed Rosenhaus to contact him when there was what he considered a "fair" offer on the table.
"Positive that they met face to face," Gore said. "Drew felt good about everything, (about) the talk."
The 28-year-old Gore, third on San Francisco's career rushing list heading into his seventh NFL season, had repeatedly said he wanted a new long-term deal before the Sept. 11 season opener against Seattle.
Both sides had been throwing around plenty of praise for the other party. 49ers team President Jed York and general manager Trent Baalke said they wanted Gore to be a "49er for life."
Gore said he even spoke to Baalke about working for the organization when he's done playing.
Gore, who missed the final five games last season with a broken right hip, held out for the first four days of training camp, but has been his energetic, focused self on the field ever since.
Gore needs 931 yards to become the franchise's all-time leading rusher. While that is a goal, he also wants to have a big year to help turn the 49ers around after eight straight seasons without a playoff berth or winning record.
He ran for 853 yards and three touchdowns last year before getting hurt in his sixth NFL season. Gore also caught 46 passes for 452 yards and two TDs. His 24 100-yard rushing games are the most in 49ers history.
The 49ers rewarded two other key players with long-term contracts last year.
Tight end Vernon Davis signed a five-year extension worth $37 million overall, including $34 million guaranteed, a night before the 2010 season opener. That made him the highest-paid tight end in NFL history.
In May of last year, All-Pro linebacker Patrick Willis received a $50 million, five-year contract extension that takes him through the 2016 season and includes $29 million in guaranteed money. He earns $10 million per season.
Information from The Associated Press contributed to this report.