Joe Cardle slotted in his eighth of the season before setting up Kallum Higginbotham to extend the Pars' lead.
Dumbarton's Craig Barr hit the crossbar with a second-half header but the Sons then had Andy Dowie sent off for two bookings.
Substitutes Nicky Clark and Andy Ryan added late goals to add gloss to the visitors' victory.
That is four wins on the bounce for Allan Johnston's men and on this form Dunfermline appear to be more than capable of sustaining a promotion challenge.
Of the six players playing in midfield or attack, only Nate Wedderburn really sits back. That security allowed Cardle, Higginbotham, Declan McManus, Dean Shiels and Callum Smith to roam forward in the first half.
Cardle converted at the back post after a messy scramble following good initial play down the right by McManus.
A superb counter-attack brought the Pars their second, as Higginbotham rolled the ball calmly into the far corner from a fairly tight angle.
Dumbarton nearly reduced the deficit, but Barr's header bounced off the woodwork after he had connected with Tom Walsh's corner.
The Sons also felt aggrieved not to be given a penalty when Ally Roy appeared to be clipped just inside the box.
Dowie was given his marching orders with 15 minutes to go, before Clark made his comeback from an ankle injury to head in David Hopkirk's cross.
Clark then back-heeled to tee up another substitute Ryan for a well-executed, low curled shot into the far left corner.
Dunfermline manager Allan Johnston: "I'm happy but I'm realistic as well because we know it's only the start of the season. We've started really strongly, we've got a really good, competitive squad and we've got people that can score goals.
"We're defending really well as well, so it's a good balance to have. We've just to make sure we keep up that kind of performance.
"I don't think we lacked confidence last season, it was a step up and it took us a bit of time to get in our stride. It's about consistency and coming to places like Dumbarton and winning. We can't take our foot off the gas."
Dumbarton manager Stevie Aitken: "We gave Dunfermline a two-goal start and you can't do that with a team of the quality of Dunfermline. There was indecision by the goalkeeper in the first one, then we gave the ball away cheaply for the second.
"Second half there was plenty of endeavour and we hit the crossbar, but it was a disappointing day.
"Danny Handling has come in and has this problem with his knee we weren't aware of. We don't know what's wrong with it, but we can't go into a game having to take a player off after 10 minutes because of a knee injury - so we'll have to get that looked at."
Match ends, Dumbarton 0, Dunfermline Athletic 4.
Second Half ends, Dumbarton 0, Dunfermline Athletic 4.
Attempt blocked. Christian Nade (Dumbarton) right footed shot from outside the box is blocked.
Foul by Stuart Carswell (Dumbarton).
Kallum Higginbotham (Dunfermline Athletic) wins a free kick in the defensive half.
Goal!  Dumbarton 0, Dunfermline Athletic 4. Andy Ryan (Dunfermline Athletic) left footed shot from the right side of the box to the bottom left corner. Assisted by Nicky Clark.
Attempt saved. Kallum Higginbotham (Dunfermline Athletic) right footed shot from more than 40 yards on the left wing is saved in the centre of the goal.
Foul by Stuart Carswell (Dumbarton).
Andy Ryan (Dunfermline Athletic) wins a free kick in the defensive half.
David Smith (Dumbarton) wins a free kick in the defensive half.
Foul by David Hopkirk (Dunfermline Athletic).
Goal!  Dumbarton 0, Dunfermline Athletic 3. Nicky Clark (Dunfermline Athletic) header from very close range to the centre of the goal. Assisted by David Hopkirk.
Nathaniel Wedderburn (Dunfermline Athletic) is shown the yellow card.
Attempt saved. Craig Barr (Dumbarton) header from the centre of the box is saved in the centre of the goal.
Substitution, Dumbarton. David Wilson replaces Tom Walsh.
Attempt blocked. Kallum Higginbotham (Dunfermline Athletic) right footed shot from the left side of the box is blocked.
Substitution, Dunfermline Athletic. Nicky Clark replaces Joe Cardle.
Attempt missed. Craig Barr (Dumbarton) header from the centre of the box is just a bit too high.
Corner,  Dumbarton. Conceded by Callum Morris.
Second yellow card to Andy Dowie (Dumbarton) for a bad foul.
Attempt missed. David Hopkirk (Dunfermline Athletic) right footed shot from outside the box is high and wide to the right.
Substitution, Dumbarton. Calum Gallagher replaces Sam Wardrop.
Foul by David Hopkirk (Dunfermline Athletic).
Kyle Hutton (Dumbarton) wins a free kick in the defensive half.
Corner,  Dumbarton. Conceded by Callum Morris.
Craig Barr (Dumbarton) hits the bar with a right footed shot from very close range.
Corner,  Dumbarton. Conceded by Callum Morris.
Attempt missed. David Hopkirk (Dunfermline Athletic) right footed shot from the centre of the box is close, but misses to the right.
Corner,  Dunfermline Athletic. Conceded by Sam Wardrop.
Attempt missed. Andy Ryan (Dunfermline Athletic) left footed shot from outside the box is just a bit too high from a direct free kick.
Kallum Higginbotham (Dunfermline Athletic) wins a free kick in the defensive half.
Foul by Christopher McLaughlin (Dumbarton).
David Hopkirk (Dunfermline Athletic) wins a free kick in the defensive half.
Foul by Tom Walsh (Dumbarton).
Calum Smith (Dunfermline Athletic) wins a free kick in the defensive half.
Foul by Stuart Carswell (Dumbarton).
Attempt saved. Nathaniel Wedderburn (Dunfermline Athletic) right footed shot from outside the box is saved in the centre of the goal.
Substitution, Dunfermline Athletic. Andy Ryan replaces Calum Smith.
Substitution, Dunfermline Athletic. David Hopkirk replaces Declan McManus.
Declan McManus (Dunfermline Athletic) wins a free kick in the defensive half.
Dunfermline climbed to the top of the Championship with an emphatic victory at Dumbarton.