By Chris Harris at Emirates Stadium
Ramsey - scorer of the winning goal in the 2014 final - came off the bench to finish from close range after Hector Bellerin and Campbell had opened up the Sunderland defence.
And Bellerin set up the third as well, his low cross finding Giroud at the far post.
Arsenal’s unbeaten run in the FA Cup now stretches to 13 games - and as they proved here, they have no intention of loosening their grip on the trophy.
SETTING THE SCENE
Arsenal have been the FA Cup’s dominant force over the past two years - and in football history for that matter.
Back-to-back Wembley wins over Hull City and Aston Villa took the Gunners to a record 12 triumphs, and they went into their latest cup quest looking to emulate Wanderers and Blackburn Rovers, who each won three in a row in the 19th century.
Wenger had never lost in the third round of the competition - no mean feat given the precariousness of a cup run - but he tends to rotate his squad for these occasions and opted for five changes. In came Gibbs, Gabriel, Calum Chambers, Campbell and 19-year-old Iwobi while Mesut Ozil was rested.
This was Wenger’s 98th FA Cup game as Arsenal manager. His first and second were also against Sunderland back in 1997, Dennis Bergkamp and Stephen Hughes taking the Gunners through after a replay.
With Ozil enjoying a well-deserved rest, there was a vacancy in the No 10 role. In the event no one filled it exclusively with Alex Oxlade-Chamberlain and Iwobi operating just in front of Chambers in what looked like a 4-1-4-1 formation.
It took a new-look Arsenal side time to gel and Sunderland had the first notable shot of the match, Lens firing just wide of Cech’s right-hand post.
His opposite number, Jordan Pickford, was called into action when Arsenal moved at pace through the centre. Oxlade-Chamberlain found Giroud and the Frenchman teed up Gibbs for a powerful side-foot that Pickford blocked.
Gibbs stopped Lens in his tracks at the other end but his pass to Koscielny was anticipated by the Sunderland forward. Lens dispossessed Koscielny and slammed a right-foot shot past Cech.
The heavens opened; Arsenal looked for a response.
Iwobi glided past two challenges to fashion a shooting chance but Pickford got in the way again. He could do nothing about Campbell’s strike though, a crisp first-time finish from Walcott’s precise cross after more good work from Iwobi.
Pickford was almost caught out by Walcott’s skidding shot from distance, padding the ball tentatively towards Campbell - but just too high for the Costa Rica star.
Arsenal, more assertive after the break, started to find gaps in the Sunderland backline.
Iwobi, growing in confidence all the time, threaded a cute pass through to Campbell, but his prod past Pickford was hacked clear before it crossed the line.
Iwobi tested Pickford with a low shot but it was Oxlade-Chamberlain who went closest, twisting and turning before curling a fine effort against the post.
Walcott’s deft touch played in Campbell for a one-on-one that saw Pickford come out on top, but it wasn’t all Arsenal.
The woodwork came to their rescue at the other end after DeAndre Yedlin beat Walcott and crossed for Fletcher to crash a header off the bar. Duncan Watmore met the loose ball on the volley but couldn’t keep it down.
Ramsey and Arteta replaced Iwobi and Chambers, and Ramsey was straight into the thick of the action, finding Gibbs for a low cross that Giroud almost turned in. Gibbs provided the ammunition again with another good overlap, only for Walcott to shoot straight at Pickford.
Sunderland were a threat on the counter-attack but Arsenal looked the more likely winners - and so it proved.
Again, Campbell was the catalyst with a splendid return pass to Bellerin that opened up the Sunderland defence. Bellerin squared and Ramsey tucked the ball past Pickford.
The third goal was not far behind and it came from the same source. This time Oxlade-Chamberlain set Bellerin clear on the right with a wonderful pass, played with the outside of his right boot. Bellerin crossed low and Giroud slotted in at the far post.
Giroud could have had a penalty moments later but was denied by referee Martin Atkinson. Danny Graham forced a save from Cech while the home fans were still jeering that decision, but in the end it mattered little.
Arsenal are back on the road to Wembley.
- Gabriel Yellow Card
- Koscielny (C)
- Campbell 81 Goal!
- Chambers 67
- Iwobi 66
- Giroud Goal!
- Arteta 67
- Reine Adelaide 81
- Ramsey 66 Goal!
- O'Shea (C) 65
- van Aanholt
- Lens Goal!
- Cattermole 57
- Fletcher 77
- M'Vila 57
- Mavrias 77
- Jones 65