The victory followed a nose defeat from favoured Restless Rider in the Golden Rod (G2) for fillies two races earlier. It also awarded Signalman with 10 additional points toward a spot in the 2019 Kentucky Derby.
Jockey Brian Hernandez Jr was aboard for both races.
"I love the way Brian rode him today; it made up for the (Golden Rod) when we thought we were a cinch," McPeek said. "This is what we all work for.
"He’ll get a little rest, probably at Payson Park for about a month. Then, we’ll ease him back into things and look at races like the Blue Grass down the road. We’ll let him tell us but obviously the big one is in May."
The Blue Grass (G2) is the final major Derby prep in Kentucky and runs April 6 at Keeneland.
Signalman entered the Kentucky Jockey Club off two on-the-board efforts against Grade 1 company. He ran second to Knicks Go in the Breeders’ Futurity (G1) and was third behind Game Winner and Knicks Go in the Breeders’ Cup Juvenile (G1).
Knicks Go, a longshot in both previous races, was the favourite in Saturday's race. He was sent from the outside along with Topper T, who set early fractions in 23.12 and 46.83. Signalman broke from the rail and saved ground a few lengths off the lead.
Once three-quarters of a mile went in 1:12.23, the speed began to backpedal and Signalman was poised to take over. Plus, Que Parfait and Limonite rallied, but Signalman was best by a neck.
He completed the 1 1/16 miles in 1:45.29.
"This horse always gave me a lot of confidence," Hernandez said. "We were able to work out the best trip possible in the Breeders’ Cup Juvenile from the 14-hole. Today, I was able to get him up into the race early and he really showed what he could do.
"You’re always fortunate to have the horse under you and today we did. Down the lane he was actually looking over at the TV screen. Even with the little quirks he still shows a lot of promise. He’ll be exciting down the road."
Signalman, a son of General Quarters, was a US$32,000 yearling purchase at last year's Fasig-Tipton October Sale. He has now made US$448,990 for owners M. Tommie Lewis, David A. Bersen, LLC and Magdalena Racing.
"He was a big, strong horse when he went through the sales ring and today he still is that type of horse," McPeek said. "He’s taken us a long way so far and it’s been a lot of fun."
The colt is tied in second with Knicks Go on the "Road to the Kentucky Derby." Both have 18 points, while Game Winner leads with 30.