"This is the first time I've ever sung in public," he noted.
Garfield then proceeded to strum the six-string and belt out the theme song from the original Spider-Man animated TV series while Fallon joined him on tambourine.
"That's the way to do it!" Fallon exclaimed after the song was over, as the studio audience cheered.
Of course, Garfield's other half, Emma Stone, also proved her ability to carry a tune (or, should we say, lip-sync a tune) during her visit to The Tonight Show earlier in the week when she memorably mouthed the words to Blues Traveler's "Hook" and DJ Khaled's "All I Do Is Win."
"She's just magic," Garfield gushed to Fallon about his gal's impressive performance.
(E! and The Tonight Show Starring Jimmy Fallon are both part of the NBCUniversal family.)