Mad and penguin are both right: “host” fits just fine.
An alternative, especially if the event is more on the entertainment side of things (instead of, say, a series of scientific presentations) would be the appropriate form of "emcee" (from "master of ceremonies") – see the entry from M-W below (it also seems to work in BE).
em·cee | \ ˌem-ˈsē
Definition of emcee
(Entry 1 of 2)
: master of ceremonies especially : a person who acts as host for a program of entertainment The emcee primes the crowd and rock music pulses, bolstered by lasers and fireworks. — Allison Glock
Definition of emcee (Entry 2 of 2)
: to act as master of ceremonies of emcee an awards dinner
: to act as master of ceremonies
And, if you switch there to the Thesaurus view, you'll see that "host" in a synonym.