Sedgwick's Millers future had been shrouded in doubt after contract talks with the winger had stalled.
Moore had claimed the 22-year-old's agent Micky Walsh had been 'living in cuckoo land' for making 'ridiculous demands' to keep Sedgwick at the club.
But Moore has now bypassed Walsh and negotiated directly with Sedgwick to keep him out of the clutches of Premiership new boys West Brom.
The flying winger's present deal is due to expire next summer and Baggies boss Gary Megson had been monitoring the situation closely.
Moore, though, now looks able to plot for the new campaign with Sedgwick an integral part of his plans.
He said: "It looks like we'll be keeping him on a new three-year contract."
