Benzema opened the scoring inside three minutes of the friendly at the Stade de France on Saturday, reacting quickest to a parried Bacary Sagna effort, before Paul Pogba doubled the advantage after the interval.
Ricardo Quaresma pulled one back from the spot before time was up, but it proved a mere consolation for a Portugal side who had struggled to break down a resolute French defence.
Benzema, who was replaced by Andre-Pierre Gignac in the closing stages, revealed to French radio station RTL after the match that he would undergo an X-ray on the toe issue that casts doubt over his involvement in Tuesday's clash with Armenia.
"I have an X-ray tomorrow," he said. "I received two blows to the toe."
Coach Didier Deschamps, meanwhile, declared himself delighted with his side's collective effort as they continued preparations to host Euro 2016.
"There was a common desire to get things done," he told TF1. "It's good to keep that dynamic.
"The players who already have experience know the system well.
"There are others coming through and I have to give them time to play.
"I felt an affinity and a common mind to get the win.
"We faced a great team in Portugal. This is a very good result for us."
