The Wales midfielder continued his blistering run of form when he was alert to guide Mesut Ozil's cross over home goalkeeper David Marshall with a looping header on 29 minutes.
Substitute Mathieu Flamini put a gloss on the scoreline when he bounded onto another Ozil pass to thump the ball beyond Marshall on 86 minutes from 14 yards.
Ramsey contributed his second goal of the day two minutes into injury time and his 13th goal for his club in all competitions this season when he walloped into the net from substitute Theo Walcott's pass with Cardiff caught on the break. Ramsey refused to celebrate his goals, but must derive enormous satisfaction from such an afternoon.
Ozil has now unearthed more assists than any other Premier League player this season since his £42 million summer move from Real Madrid, a price tag that is beginning to look like a huge bargain.
The winning margin was little more than Arsenal deserved for a largely dominant performance that should have earned them more goals, especially in the first half when Cardiff could hardly gain any meaningful period of pressure.
The home side's best attempt of the match came in the 52nd minute when Wojciech Szczesny was forced to claw out Fraizer Campbell's header, but Arsenal were a class apart in the key areas against a collection of honest triers.
2' - WILSHERE WALLOPS BAR: Jack Wilshere sees a shot come back off the bar from distance. What an effort that is. So unfortunate from 20 yards out.
15'- GIROUD SPURNS OPPORTUNITY: Glorious chance for Giroud. Through on goal from the Ozil flick, but no flag came and Giroud stopped enabling Cardiff to clear the danger with a Caulker block. Astonishing passage of play.
29' - RAMSEY STRIKE: Ramsey heads into the corner of the net from the Ozil cross. Brilliant finish from the former Cardiff player. 14 yards or so out. What a technique that is.
48' - MORE RAMSEY MAGIC: Fine run and cross by Ramsey. Comes up with the cutback for Giroud, whose shot is cleared off the line by Turner with Marshall beaten.
53' - SUPERB SZCZESNY STOP: Szczesny with a brilliant diving save low to his right to make the stop from the Campbell header. Lovely flick on by Kim. Gibbs well beaten in the air by Campbell.
86' - FLAMINI STRIKE: Flamini thumps into the net. Brilliant finish from the Ozil pass. 12 yards out on the run. An outstanding team goal.
90+2' - RAMSEY ADDS A THIRD: Ramsey slams home his side's third of the day as he buries the ball in the net from the Walcott pass. Brilliant break and finish from the visitors. 3-0 now. Superb stuff.
Aaron Ramsey has scored 14 Premier League goals for Arsenal; he has equalled John Hartson’s record for most Premier League goals for the club from a Welsh player. Hartson scored 14 between 1995 and 1997.
Arsenal have recorded their biggest Premier League away win for nearly a year – since their 5-2 victory at Reading on December 17th 2012.
This was Cardiff’s worst top-flight home defeat since a 4-0 loss to Leicester in April 1962.
Olivier Giroud waiting for an offside flag that never came - The one man that should be happier than most with this result is the French striker. Giroud inexplicably stopped playing on 15 minutes after Jack Wilshere had picked him out with a lovely pass. Replays showed Mesut Ozil did not touch the ball when he was played in. Giroud was onside and only had Marshall to beat, but his hesitancy enabled Steven Caulker to clear. Moral to the story? Always play to the whistle. Or always play when there is no whistle.
MAN OF THE MATCH
Aaron Ramsey (Arsenal): Who do you give it to? Ramsey or Ozil? We'll give it to Ramsey after the toss of a coin. Just so much class throughout this Arsenal side. They were a joy to watch at times. The bandwagon rolls on. At this rate, it will take some derailing.
Cardiff: Marshall 6, Taylor 5, Caulker 6, Turner 7, Whittingham 5, Medel 5, Campbell 6, Kim 5, Mutch 6, Cowie 6, Theophile-Catherine 5. Subs: Cornelius 6, Odemwingie 5, Noone 6.
Arsenal: Szczesny 7, Sagna 7, Mertesacker 7, Koscielny 7, Gibbs 7, Arteta 7, Wilshere 7, Ramsey 9, Ozil 9, Cazorla 7, Giroud 6. Subs: Monreal 6, Flamini 7, Walcott 7.
THE MATCH IN A TWEET