)
The 32-year-old proved he has returned to his best after two months out with personal problems after the first coronavirus lockdown last year.
The Sloven striker was omnipresent for the northerners with captain Papu Gomez still frozen out after clashing with coach Gian Piero Gasperini.
Ilicic gave the visitors the advantage after half an hour, with an impressive solo run up the right flank, dribbling past three defenders to fire in through Kamil Glik's legs into goal.
He was a denied a second by the post shortly after, having provided perfect crosses for Robin Gosens and Duvan Zapata, who squandered their chances in the first half.
)
)
)
Marco Sau pulled Benevento level five minutes after the break, with Zapata having a goal ruled offside.
But Ilicic had a role in Atalanta's next two goals, Benevento goalkeeper Lorenzo Montipo pushing an effort from the Slovenian into the path of Rafael Toloi who cooly finished off after 69 minutes.
Two minutes later Ilicic was again on hand with the perfect cross for Zapata to send in the third from close range.
Substitute Luis Muriel curled in four minutes from time, for his 10th goal this campaign.
Atalanta go above champions Juventus by a point, with the Bergamo side now six points adrift of leaders AC Milan who host Torino later on Saturday.
Milan are looking to extend their one-point advantage on city rivals Inter who travel to third-placed Roma on Sunday.
Zlatan Ibrahimovic has returned to the Milan squad after seven weeks out injured, with the 39-year-old having missed eight league games.
On Sunday, fifth-placed Juve face a tough tie at home against Sassuolo in sixth.
Andrea Pirlo's side are without three players who are suffering from coronavirus in Alex Sandro, Juan Cuadrado, and Matthijs De Ligt.
ea/iwd