Observation Haki lets you sense intent. The Voice of All Things lets you hear the soul of inanimate objects and animals (like Zunesha or the Sea Kings). Luffy has consistently shown the ability to sense emotions on a primal level—he knew Momonosuke was afraid, he sensed the sadness of Laboon, he heard the voice of the Sea Kings.
Luffy is the literal opposite. He is a hurricane of emotion. He fights with joy, rage, and impulsive chaos. In Gear 5, he laughs so hard he forgets to dodge. can luffy use observation haki
The proof? Luffy dodges Katakuri’s Mochi thrust by seeing his own head getting punched before it happens. He later uses this against Kaido to dodge Bolo Breath . Yes, Luffy can canonically see the future. Observation Haki lets you sense intent
But he will never, ever use it to avoid a punch that he knows he can survive. Because that’s boring. And for the man who will become the Pirate King, a boring fight is worse than a lost one. Luffy is the literal opposite
If you type "Can Luffy use Observation Haki" into a search bar, the short answer is a resounding yes . He’s used it dozens of times.
His formal awakening came during the brutal two-year training on Rusukaina with Silvers Rayleigh. By the time he returned to the Sabaody Archipelago, he was a certified user. We saw it explicitly when he dodged the Pacifista’s lasers with a calm smile, and again when he sensed the presence of 100,000 Fishman pirates on Gyojin Island.