Gilbert outsprinted Milan-San Remo winner Michal Kwiatkowski to claim his fourth Amstel Gold Race title, finishing the 264km race in 6:33:55.
Ten seconds behind the two former Amstel Gold Race champions was Switzerland’s Michael Albasini.
“Riding such a close race I knew that if I was able to give just one or two per cent more, it would really make the difference,” said Gilbert.
“You have to push through the pain and go past your limit in a race like this and that’s what I did today,” said the Tour of Flanders winner.
“It was a hard final and we all deserved the win but in the end there is only one winner.”
The two fought a hard battle over the last kilometre as Kwiatkowski forced Gilbert to the front into the strong headwind before accelerating into the lead.
However, the 26-year-old Milan-San Remo champion was unable to maintain his pace and Gilbert proved he had the stronger legs as he fought his way back to take the title.
“We rode together from about 40km out and I said to him that we’d ride together until the last kilometre and then see who took it,” said the Quick-Step Floors leader.
“He surprised me in the sprint but it was a headwind so I didn’t panic, and I saw I was getting closer and closer, and it was perfect for me in the end.”
It was on the Bemelberg that the duo initiated their attack and broke away from the lead group that had formed on the Kruisberg.
The lead group included Gilbert, Kwiatkowski, Albasini, Ion Izagirre, Sergio Henao, Jose Rojas, Bert-Jan Lindeman and Nathan Haas.
Once Gilbert and Kwiatkowski had broken from the group they left a struggling bunch to make chase.
More results from the Ardennes Classic can be seen here.