- May 12 - The new lineup for The Rentals was announced. It includes original backup vocalist Rachel Haden, Sara Radle on vocals/multiple instruments, Ben Pringle (from Nerf Herder) on synth, Lauren Chipman on viola/vocals and Dan Joeright on drums.
- June 8 - Rivers Cuomo graduates from Harvard.
- June 18 - Rivers Cuomo gets married to Kyoko Ito Cuomo in Malibu, California.
- June 19 - Rivers Cuomo and his new wife Kyoko Ito Cuomo fly to Germany to see one of the United States soccer matches in the World Cup finals as part of their honeymoon.
- September 29 - Weezer files a lawsuit against Miller Brewing Company for using the band's name/image in several ads that ran in Rolling Stone magazine in 2004 without permission.
- December 8 - The video of the "Making of Make Believe" is released.
- December 9 - After more than a year of delays, the Weezer "Holiday Treat '05 PS live in Tokyo 12/22/05" is released.
- December 10 - The video "Summer Scrapbook '05 Vol. 1" is released
- December 29 - Factory Girl which stars Weezer members Brian Bell and Patrick Wilson opens in select theaters.