Raheem Mostert ran in four touchdowns as the 49ers took control, with the Packers, who trailed 27-0 at half-time, scoring two Aaron Jones touchdowns and another from Jace Sternberger.
The Chiefs beat the Tennessee Titans 35-24 in the AFC Championship game earlier on Sunday to secure a first Super Bowl appearance in 50 years.
This will be the 49ers' first Super Bowl since 2013 when they lost 34-31 to the Baltimore Ravens in New Orleans.