On-loan Everton striker Romelu Lukaku scored twice in a 2-1 Group A victory over Croatia on Friday to guarantee Belgium a place in their first major tournament since 1998.
Kompany, who is currently sidelined with a thigh injury, was absent from the national squad that travelled to Zagreb, but took to Twitter to congratulate his compatriots after their win.
He tweeted: "To me, football is about big moments and achievements. I am proud of my country and I am proud of our team. Let's improve and be the best!"
Kompany, 27, has made 56 international caps, scoring four goals, since debuting in 2004.