Raheem Sterling headed Man City into the lead after being set-up by Joao Cancelo with 18 minutes played.
Chris Wood had a goal ruled out shortly afterwards as Bruno Guimaraes was penalised by the offside flag.
Aymeric Laporte pounced on a Martin Dubravka error to make it 2-0 at half-time before a Rodri header made it 3-0 on the hour mark.
Late goals from Phil Foden and another from Raheem Sterling added some gloss to the scoreline late on.
After losing 1-0 at home to Liverpool last weekend, Howe made three changes to the starting line-up at the Etihad Stadium.
Jamaal Lascelles comes into the side in place of Fabian Schar, who was forced off with an ankle injury last time out.
Sean Longstaff and Chris Wood also came into the side for Jonjo Shelvey and Joe Willock, who dropped out entirely.
But there was a couple of welcome returns on the bench as Kieran Trippier and Callum Wilson both came on after lengthy spells on the sidelines due to injury.
Here are our player ratings from the match at the Etihad Stadium...
Aymeric Laporte pounced on a Martin Dubravka error to make it 2-0 at half-time before a Rodri header made it 3-0 on the hour mark.
9. Miguel Almiron - 4
A very quiet display and didn’t show enough quality on the rare occasions he did get the ball.
10. Allan Saint-Maximin - 5
Put a good cross in for Wood early on but didn’t track back for the opening goal. Was Newcastle’s biggest threat going forward but left Targett exposed down the left side.
11. Chris Wood - 4
Wasted a great chance early on with a header and had a goal ruled out for offside in the first half.
12. Callum Wilson - 6
On for Wood 68: Hit a one on one shot straight at Ederson. Got into some decent areas.