It was reported yesterday that Moore died over the weekend while on holiday in Spain's Costa del Sol region.
Speaking to BBC News, Geldof insisted that Moore holds a coveted ranking among the all-time great guitarists.
"Gary without question was one of the great Irish bluesmen," he said. "His playing was exceptional and beautiful."
The former Boomtown Rats frontman also credited Thin Lizzy as pioneers of the hard rock genre.
"Thin Lizzy, I think, are one of the great bands," he said. "I mean, If you don't have them, you don't have things like AC/DC [and] that whole strain…of lyrical rock and roll."
After the band's lead singer Phil Lynott died of heart failure in 1986, Geldof joined Thin Lizzy for a one-off headlining gig at the Self-Aid concert later that year.