The former world number one was included in a four-man team along with Chris Guccione, Paul Hanley and Peter Luczak.
Australian Davis Cup regulars Mark Philippoussis and Wayne Arthurs were not considered because of injury.
Australia's non-playing captain John Fitzgerald said Hewitt was certain to fill one of the singles berths and Hanley one of the doubles berths but the other two spots were both wide open for the Feb. 9-11 tie in Liege.
"I'm very happy with the team we've selected for what will undoubtedly be a tough tie against Belgium," Fitzgerald said in a statement.
"Lleyton's Davis Cup record is exceptional, and he'll get strong support from Chris, who had some terrific results this summer and Peter, who performs so well on clay.
"As for who teams up with Paul in doubles, that spot is up for grabs and we'll make a decision based on form during practice."
Teenager Brydan Klein was included as one of two hitting partners after winning the Australian Open boys' singles title while Darren Cahill was confirmed as coach.
Cahill replaced Roger Rasheed who had filled in for Wally Masur last year but withdrew from the job after quitting earlier this month as Hewitt's personal coach.
Australia have played Belgium twice in Davis Cup, in 1922 and 1991, winning both times.