Mbappe – who won the early penalty from which Neymar put PSG ahead – missed a glut of gilt-edged chances in Sunday's clash, but turned on the style after the hour.
Presnel Kimpembe's VAR-assisted red card had threatened to complicate matters for Thomas Tuchel, only for Lyon's Lucas Tousart to receive his marching orders on the stroke of half-time.
And PSG did not look back, Mbappe completing an eight-minute hat-trick – his first for the club – before hammering in a fourth to cap off a record ninth straight win at the start of the Ligue 1 season.
Nabil Fekir's ankle injury dealt Lyon an early blow, and matters were made worse for the visitors when Neymar sent Anthony Lopes the wrong way from the spot, but PSG found themselves down to 10 in the 32nd minute.
3 - Paris have scored at least three goals in each of their first eight games in Ligue 1, the first time that a team accomplish such a performance in the top-flight’s history. Power. pic.twitter.com/AGTM6ILEL1— OptaJean (@OptaJean) October 7, 2018
Kimpembe dived in on Tanguy Ndombele and, despite initially awarding a booking, referee Antony Gautier overturned his decision after assessing the replays, brandishing a straight red card.
Lyon's advantage was short lived, however, Tousart picking up a second yellow card for scything down Mbappe, who was denied a certain goal by Lopes after the restart.
Mawell Cornet almost scored a freak equaliser when he deflected Thiago Silva's clearance onto the woodwork but, having hit the upright himself, Mbappe finally had his goal after the hour – his low strike rattling in off the inside of each post.
That opened the floodgates, Mbappe tucking in a second from Marquinhos' cut-back before rounding off an incredible hat-trick with a high finish past Lopes.
There would be more drama – Mbappe drilling home at the culmination of Neymar's mazy run – while Gianluigi Buffon was forced into a save to deny Memphis Depay a late consolation.
What does it mean: Rampant PSG eight points clear
It has been a sensational start for Thomas Tuchel in Ligue 1, and with records falling, the former Borussia Dortmund boss could be forgiven for assuming the title is already wrapped up.
PSG are eight points clear and are showing no signs of slowing down.
Magical Mbappe shows no mercy
On a different day, Mbappe could easily have had seven goals. The youngster wasted good chances either side of the interval, but once he had his first, Lyon's defence crumbled before him.
Neymar was brought in to be PSG's superstar, but there is no doubting Mbappe's credentials as the main man in Paris.
Kimpembe, Tousart show their immaturity
Both Kimpembe and Tousart have shown maturity beyond their years over the past few seasons, but the youngsters let their inexperience get the better of them on Sunday.
Kimpembe's rash challenge on Ndombele was dangerous, and deserved a red, only for Tousart's needless lunge on Mbappe to cancel out Lyon's numerical advantage.
Key Opta stats:
- PSG are unbeaten in their last 11 home games in Ligue 1 against Lyon (W9 D2), their longest streak ever against them in the top flight. The 5-0 win is PSG's biggest ever against Lyon in all competitions.
- The Parisiens are the first team ever to win each of their first nine games of a single season in the history of Ligue 1.
- PSG have lost only once in their last 47 home games in Ligue 1 (W38 D7).
- Thomas Tuchel's side have scored at least three goals in each of their first nine games in Ligue 1, the first time that a team has accomplished such a performance in the top flight's history.
- Kylian Mbappe is the fastest player (13 minutes) to score four-plus goals in Ligue 1 over the last 45 seasons. He is the youngest player (19 years and nine months) to score four goals in one game in Ligue 1 over the last 45 seasons.
- Presnel Kimpembe has received three red cards since the beginning of last season in Ligue 1, no player has received more in Ligue 1 in that period.