The 49ers' official website issued a press release on the development:
"The San Francisco 49ers have signed quarterback Colin Kaepernick to a six-year contract extension through the 2020 season.
"'Colin's hard work and dedication have played an integral role in the recent success of the 49ers organization,' said 49ers general manager Trent Baalke. 'His work ethic, leadership and on-field production have positively influenced our team, and we look forward to his continued growth in all areas.'
"'Our organization always looks to reward our players for their contributions and commitment to the team. Colin's agents, Scott Smith and Jason Bernstein, along with Paraag Marathe and Brian Hampton, should be commended for working diligently to reach an agreement.'"
CSN Bay Area's Matt Maiocco says Kaepernick's deal could reach up to $126 million.
"The six-year extension includes more than $60 million in guaranteed money, a source said. The total package of the deal can reach $126 million. Kaepernick is scheduled to take part in a press conference at 2:30 p.m. at 49ers headquarters in Santa Clara to announce the deal.
"Kaepernick was scheduled to enter the final year of his original four-year, $5.129 million contract he signed as a second round draft pick in 2011.
"The sides resumed contract talks on Tuesday in Santa Clara. It was the first time since the NFL Scouting Combine in Indianapolis in February that the sides met face-to-face. It did not take long for them to hammer out the details on the richest contract in 49ers history.
"Baalke stated his goal in March was to sign Kaepernick to a long-term extension before the opening of training camp. The 49ers accomplished the landmark deal with seven weeks to spare.
"Aaron Rodgers is the highest-paid quarterback in the NFL at $22 million per season. Matt Ryan, Joe Flacco and Drew Brees each make $20 million or more per season. Peyton Manning, Jay Cutler, Tony Romo and Matthew Stafford also earn at least $17.666 million annually."
According to SFGate.com's Eric Branch, Kaepernick was supposed to earn a base salary of $973,766 next season, the last year of his rookie contract. San Francisco received $6.6 million in salary-cap space on June 1 when cornerback Carlos Rogers' deal was taken off their books, which puts the team around $8 million under the cap.
Moments after signing the deal with a quill while wearing socks with dollar bills on them, Kaepernick told 49ers.com's Taylor Price he will be out to prove he is worth the contract he signed.
"I'm going to work to make sure I'm worth every penny of this. That's something I feel like I can do.
"I'm trying to win as many Super Bowls as I can. That's not necessarily realistic to win it every single year, but that's what your goal is.
"We can get back to football and get back to trying to win a Super Bowl.
"To me it's something I feel like I'm always striving to be in that group, in that elite group in the NFL.
"Whatever comes along with that, comes along with it. For me, I'm worried about being the best player that I can and try to help this organization win as many games as we can.
"They (49ers) felt like this was something they would be able to get other players. I'm very grateful for it. There have been too many people to help me get to this position....I'm very grateful for my teammates as well. I wouldn't be there without them.
"I don't think my motivation is money-driven. I think it's driven by the success I can have on the field...with my teammates."
ESPN's Bill Williamson offers his take on the Kaepernick extension.
"He will turn 27 in November. He has just 29 career starts. He is still learning the game. He is not in his prime yet.
"And he is not overpaid. The average money is in line with what the better quarterbacks in the NFL make. Don't get tripped up by the guaranteed money. OK, it's a record. And it will likely be surpassed by the next quarterback who signs a long-term extension.
"The reality is quarterbacks get paid in the NFL. Believe me, every NFL team wants to have to pay their quarterback big. If not, it means the team doesn't have their answer at the position. If a quarterback is good, he is going to get paid. Kapernick has reached that point.
"If you don't think Kaepernick has arrived, please think again. He is 21-8 in his NFL starts and has already won three road playoff games. He has been to the NFC Championship Game three times -- starting two -- and to the Super Bowl.
"He is entering just his second full season as a starter, and he's that accomplished. For those who might argue that he hasn't reached his potential, I offer this: How is that a bad thing?
"He is only going to improve. Yes, Kaepernick does need to work on his pocket presence and yes, he's not as far along with his read progressions as the team would like.
"But he will master those areas."
Kaepernick has thrown for 5,046 yards, 31 touchdowns and 11 interceptions in his three-year NFL career. He has also rushed for 937 yards and nine touchdowns, per ESPN stats.