Lukaku reached the milestone when scoring Belgium’s opener, and five more goals followed in a one-way first half.
Nacer Chadli and a Cristian Brolli own goal made it 3-0 before Lukaku scored his second, with Toby Alderweireld and Youri Tielemans putting Belgium 6-0 up at half-time.
Substitutes Christian Benteke and Yari Verschaeren were on target after the break before Timothy Castagne scored late on to complete the rout.
Elsewhere, Croatia solidified their place at the top of Group E with a home 3-0 win over Hungary, who are now four points off top in third.
Luka Modric opened the scoring before Bruno Petkovic’s double put Croatia in control.
Austria defender Martin Hinteregger scored a goal that any striker would have been proud of to set up a 3-1 win over Israel in Euro 2020 qualifying on Thursday.
The Austrians moved above Slovenia, who were surprised 2-1 away to North Macedonia with a Elif Elmas brace, into the top two of Group G.
Robert Lewandowski scored a hat-trick to give leaders Poland a comfortable 3-0 win away to basement side Latvia.
The top two in the six-team group qualify for Euro 2020.
Additional reporting from Reuters