The Belgian rider opted to take a break from competitive action following a disappointing spring during which he failed to win a Classic.
That was in stark contrast to last season, when he became just the second man to claim all three Ardennes Classics in a single year.
Gilbert, who has been hampered by injury and illness this season, posted a third-place finish in La Fleche Wallonne a month ago in his last outing on a bike.
But the 29-year-old is now ready to return, with the defence of his 2011 Tour of Belgium title first on the agenda.
"It was good for me to spend one month at home, to be able to work hard and start a new base and build new form and condition," he said.
The five-day stage race, which begins on Wednesday, ends with a time trial and a tough final stage which includes climbs from La Flèche-Wallonne and Liège-Bastogne-Liège.
"I know against the time trial specialists, I will lose time," Gilbert said. "The last stage is tricky in the area of Huy, so if I see that I can't aim for the general classification, I will try to win a stage."
The Tour of Beligium was one of two stage races Gilbert won last year, his other victory coming at the Ster ZLM Toer.