Yaya Toure scored the pick of City's goals in a sparkling display at Etihad Stadium with a sublime 50th-minute free kick, adding to first-half goals by David Silva and Sergio Aguero and a late strike by substitute Samir Nasri.
It was a complete performance — and a powerful response to impressive wins by Manchester United and Chelsea on the opening weekend of the season. It could be some battle for the title this season between England's leading three clubs.
"The most pleasing thing is the way the team played for 90 minutes," said Pellegrini, who often stood motionless in his technical area, hands in his pockets or arms folded as his team dismantled Newcastle.
"Not depending if we were winning by one, two or three goals, I think we had from the beginning an attitude to play as an aggressive team, an offensive team. And we continued doing that for 90 minutes. The most important thing is to win. But after, it's the way we did it."
On this evidence, it could be another season of struggle for Newcastle, which played the second half with 10 men after Steven Taylor's straight red card for swinging his arm into the face of Aguero in first-half injury time.
Manager Alan Pardew was already without key midfielder Yohan Cabaye, who wasn't included in the squad in the wake of a reported bid of 10 million pounds ($15.65 million) from Arsenal. A chastening day for the visitors was compounded by Argentina midfielder Jonas Gutierrez limping off with a left hamstring injury, making it a disastrous start to the season.
Thankfully for Newcastle, the team won't be coming up against such irresistible opponents every week.
"A lot of teams are going to struggle here," Pardew said. "They have fantastic talent."
City also had an injury setback with captain Vincent Kompany hobbling off in the 70th with a groin injury but it was an otherwise perfect evening for Pellegrini, whose team played with a swagger and fluency rarely seen in the latter days of predecessor Roberto Mancini's tenure.
The mild-mannered Chilean has kept a relatively low profile since joining from Malaga in June, wrapping up his off-season spending — totalling about 90 million pounds ($140 million) — early to give his squad plenty of time to gel.
And it really showed here.
Two of his four big-money recruits — Spain winger Jesus Navas and Brazil midfielder Fernandinho — made their first league starts and slotted seamlessly into the starting team. Navas, in particular, stood out as part of an attacking unit that ripped through Newcastle's over-run defence time and again. The score could have been double figures.
"We wanted to show people what we were capable of," said City striker Edin Dzeko, who failed to score the goal his overall performance deserved. "We scored four goals and could have had more.
"The new manager has come in and given us something different."
By the time Silva headed in from 10 yards in the sixth minute after a cross from Dzeko had been deflected into the playmaker's path, City could easily have been two up, only for great saves by Tim Krul to deny Dzeko and Aguero.
Dzeko — clearly revitalized after being on the periphery under Mancini — played a key role in Aguero's goal. He flicked Kompany's pass out of defence toward his strike partner, who got half a yard on Taylor and buried a low, angled shot in off the far post in the 22nd.
Taylor was having one of those nights, nearly giving a penalty away for handball off Aguero's goal-bound shot, and a hapless performance was further blotted when he swung an arm at Aguero as they challenged a high ball. Referee Andre Marriner had little option but to brandish a red card.
"It was completely out of character for him," Pardew said. "He has apologized."
After that, it was just a matter of how many for City.
Toure curled a sublime free kick from 25 yards into the top corner to make it 3-0, and Nasri, part of a star-studded substitutes' bench, ran onto a stray pass from Pablo Zabaleta to beat fellow France international Mathieu Debuchy to the ball and slot home left-footed from just inside the area in the 75th.
That put City top of the fledgling standings, above United.
Alvaro Negredo, another off-season signing, was brought on for the final 10 minutes. And the Spain striker thought he had grabbed a debut goal, only for his close-range strike to be wrongly ruled out off for offside.
When City won the title in the 2011-12 season, the team started with a 4-0 home win — on that occasion against Swansea. Its start to this season couldn't have been more ominous.