Higuain, who joined Juve from Napoli in a €90 million (S$137.25 million) close-season deal, pounced at the far post in the 75th minute after coming on midway through the second half.
Few observers expect Juventus to be challenged in Serie A, where it is attempting to win a record sixth consecutive title.
“It was really important to win and start well so we can approach the Porto match serenely”, Perotti said.
Juventus opened their title defence at home with German global Sami Khedira giving them the lead on 37th minute.
Fiorentina was unable to produce a single shot in the first half but Nikola Kalinic equalized in the 70th with a header following a corner.
Five minutes later however Higuain offered a glimpse of the predatory instincts that prompted Juve to trigger his release clause at Napoli.
In contrast, Roma, who last won the title in 2001, enjoyed plain sailing as their adventurous formation, featuring Mohamed Salah and Stephan El Shaarawy either side of striker Edin Dzeko, fired on all cylinders after a goal-less opening period.
The 49-year old coach said he had already picked most of his team for the season opener, and backed striker Paulo Dybala, who scored 19 goals in 34 league appearances last season, to stake his claim as one of the world’s best players this campaign.
It was also a flawless start for Roma as the Giallorossi prepare for the return leg of the Champions League playoffs on Tuesday against Porto, following a 1-1 opening leg.
Juve secured a fifth straight Scudetto last season and appeared to be cruising in the first period, but they only had Khedira’s goal to show for their dominance and almost paid the price for wayward finishing when Kalinic stole in for a shock 70th-minute equaliser.
Of the new arrivals, only Pjanic and Alves look certain to start on Saturday with Allegri expected to give Higuain more time to get in shape after he returned from his summer break looking distinctly overweight.
The Argentina striker came off the bench to seal the three points with a typical poacher’s strike a quarter of an hour from the end at the Juventus Stadium.
Salah and Dzeko produced several early chances before a sparse crowd at the Stadio Olimpico.