The Chelsea head coach was full of praise for his in-form forward, highlighting both the quality of his finishing and the movement inside the box that produced two simple close-range goals.
Villa had taken an early lead when Douglas Luiz struck inside the opening minutes, giving the hosts hope of ending their recent poor run of form. However, Pedro quickly turned the match around with two first-half goals.
The striker first equalised by slipping away from Ezri Konsa to tap in at the far post before producing a delicate chipped finish over Emiliano Martinez to put Chelsea ahead before the break. Pedro then completed his hat-trick with another close-range finish after a cross from Alejandro Garnacho.
"He's a top player and growing in confidence," Rosenior said.
"His goal with the left foot is world class, but I was really delighted with his two tap-ins. He was in the right place at the right time and we have worked really hard on that. He gets a hat-trick and it's an outstanding team performance."
The result lifts Chelsea into fifth place in the Premier League, moving them above Liverpool and to within three points of fourth-placed Villa as the race for Champions League qualification intensifies.
Pedro's treble was his first in the Premier League and took his tally to 14 league goals this season and 17 across all competitions. Only Erling Haaland has scored more non-penalty goals in the league during the current campaign.
Chelsea will now look to maintain their momentum with several important fixtures ahead, including an FA Cup clash with Wrexham and a Champions League tie against Paris Saint-Germain.
Rosenior emphasised that the victory would only matter if his side can maintain consistency over the final stretch of the campaign.
"It's only significant if we back it up," he said. "We just need to perform and if we perform at that level, we're going to be in a good place."