He is a watch aficionado (with a collection he values in the "tens of millions" of dollars), and has been on the jury at the Grand Prix d’Horlogerie de Genève. According to Mayer, his fascination with Vaughan started a "genealogical hunt" that led him to other blues guitarists, including Buddy Guy, B. King, Freddie King, Albert King, Otis Rush and Lightnin' Hopkins.
After his appearance at the 2001 South by Southwest Festival, he was signed to Aware Records, and then Columbia Records, which released his first EP, Inside Wants Out.
His following two full-length albums—Room for Squares (2001) and Heavier Things (2003)—did well commercially, achieving multi-platinum status.
Erik Crawford of All Music asked, "Is [Mayer] the consummate guitar hero exemplified when he plays a cover of Stevie Ray Vaughan's 'Lenny', or is he the teen idol that the pubescent girls shriek for after he plays 'Your Body Is a Wonderland?
'" The album was commercially successful, and while it did not sell as well as Room for Squares, it peaked at number one on the US Billboard 200 chart.
In February 2003, Mayer released a live CD and DVD of a concert in Birmingham, Alabama titled Any Given Thursday, which included songs previously not recorded, such as "Man on the Side", "Something's Missing", and Covered in Rain".