Lukaku, who turned 33 on Wednesday, has not started for Napoli this season, making seven substitute appearances and netting a goal at Verona in February, and has been in Belgium for the last two months rehabilitating after a hamstring injury.
But his role as the country’s leading scorer has seen coach Rudi Garcia gamble on his fitness for the tournament starting next month, where Belgium are in Group G along with Egypt, Iran and New Zealand.
Lukaku has scored 89 times but won the last of his 124 caps in the 4-3 home win over Wales in World Cup qualification last June.
As cover, Garcia included promising attacker Matias Fernandez-Pardo after he committed his international future to the country earlier this week.
The 21-year-old, who was born in Brussels to Italian and Spanish parents, played for Belgium at junior level but in 2024 chose to play for Spain, but subsequently did not honour a call-up to their under-20 side. He has had a strong season at Lille and is chosen in place of Lois Openda, who has not played regularly for Juventus this season.
Sporting defender Zeno Debast was also included despite being hurt in training for the Portuguese club and amid reports he might not recover in time. Debast has been a regular since Garcia took over as coach.
The timely return from injury of goalkeeper Thibaut Courtois is a bonus for the squad, but speculation that Garcia would pick four goalkeepers in his 26-man selection proved incorrect.
Garcia announced his squad in the lunchtime news bulletin on Belgian television, and it will be a fourth successive World Cup for Courtois, Lukaku, Kevin De Bruyne and Axel Witsel.
Belgium's World Cup squad:
Goalkeepers: Thibaut Courtois (Real Madrid), Senne Lammens (Manchester United), Mike Penders (Racing Strasbourg)
Defenders: Timothy Castagne (Fulham), Zeno Debast (Sporting Lisbon), Maxim De Cuyper (Brighton & Hove Albion), Koni De Winter (AC Milan), Brandon Mechele (Club Brugge), Thomas Meunier (Lille), Nathan Ngoy (Lille), Joaquin Seys (Club Brugge), Arthur Theate (Eintracht Frankfurt)
Midfielders: Kevin De Bruyne (Napoli), Amadou Onana (Aston Villa), Nicolas Raskin (Rangers), Youri Tielemans (Aston Villa), Hans Vanaken (Club Brugge), Axel Witsel (Girona)
Forwards: Charles De Ketelaere (Atalanta), Jeremy Doku (Manchester City), Matias Fernandez-Pardo (Lille), Romelu Lukaku (Napoli), Dodi Lukebakio (Benfica), Diego Moreira (Racing Strasbourg), Alexis Saelemaekers (AC Milan), Leandro Trossard (Arsenal)