The Chile international, who has been heavily linked with a summer switch to Old Trafford, featured in Saturday's 45-minute friendly defeat to AC Milan
The Chile midfielder has not featured at all during pre-season, with the midfielder having been afforded an extended break to recover from his exploit's at Brazil 2014 this summer.
Speculation was rife that Vidal had played his last game for the Old Lady, with United reportedly on the verge of luring the 27-year-old.
However, Vidal played in Juve's Trofeo TIM clash with AC Milan in Reggio Emilia on Saturday night, which, as far Allegri was concerned, more than made up for the 1-0 loss to their Serie A rivals.
"It was the first time that he's played since we have returned to training, so he's still missing something [in terms of fitness]," Allegri told Mediaset.
"The important thing, though, is that he has returned."
While Vidal now looks certain to remain in Turin, Juve are reportedly still looking to strengthen their squad before the close of the transfer window.
It has been claimed that director general Giuseppe Marotta is targeting a defender and an attacker, and Allegri admitted that he is not against the idea of making more signings.
"We [the coaching staff] are in full harmony with the club," he explained. "If there's the chance of improving the squad, the club will certainly do it."
Allegri took charge of Juve last month, after the shock resignation of Antonio Conte as coach.