While he threw an incompletion on his 26th pass, he matched Ryan Tannehill's effort from 2015, per Greg Beacham of the Associated Press.
Rivers also set the record for consecutive completions to start a game, passing Mark Brunell, who had 22 in 2006, per NFL Research.
While it could have been easier to set these marks with short throws, the quarterback was aggressive throughout the day against the Cardinals.
Trailing 10-0 when the first quarter ended, Rivers led the Chargers to 28 points in the second to grab an 18-point halftime lead. The veteran was 19-of-19 for 187 yards and two touchdowns in the first half.
Geno Smith entered the game in the fourth quarter with a 42-10 lead, allowing Rivers to finish 28-of-29 for 259 yards and three scores.
According to Joe Reedy of the Associated Press, this gives the quarterback the best single-game completion rate in NFL history.
Rivers has been accurate all season long, entering the week with a 67 percent completion rate. This would rank second-best in his 15-year career, trailing only the 69.5 percent mark in 2013, which led the NFL. Meanwhile, his 9.1 yards per attempt would be a personal best.
A missed attempt on a checkdown to Austin Ekeler in the third quarter cost him a perfect day and sole possession of the record.