Arsene Wenger’s third-placed side are aiming to qualify for the Champions League via a top-four finish for the 18th year in a row and they are well on course after a fifth successive league victory.
It was also the ideal preparation for next week’s Champions League last 16 trip to Monaco, who hold a 3-1 lead from the first leg.
Giroud broke the deadlock seconds before the break as the France striker cut in from the right edge of the penalty area to lash an unstoppable left-footed shot into the far corner.
Wales midfielder Aaron Ramsey got Arsenal’s second, and his first since December, in the 81st minute when he played a one-two with Giroud and finished with aplomb.
Mathieu Flamini came off the bench to seal the points with an 84th minute goal that lifted the Gunners four points ahead of fourth-placed Manchester United and six clear of fifth-placed Liverpool.
“It was a convincing win and a very important one as well. That’s the kind of game we want to play,” Wenger said.
“When it doesn’t work it is questioned but that is the game we love.”
Aston Villa’s revival under new manager Tim Sherwood gathered pace as they boosted their bid to avoid relegation with a crucial 4-0 win at fellow strugglers Sunderland.
Villa had scored only four away league goals all season, but they have been transformed since former Tottenham boss Sherwood took charge and have now won their last two league games to climb above Sunderland, who drop to fourth bottom after their sixth consecutive game without a win.
The visitors took the lead when Belgian striker Christian Benteke fired home in the 16th minute for his fifth goal of the season.
Just two minutes later, Gabriel Agbonlahor ran clear to slot home after Sunderland defender John O’Shea made a hash of dealing with Ciaran Clark’s pass.
Agbonlahor netted again eight minutes before half-time, prompting a group of angry Sunderland fans to surround the home bench to berate boss Gus Poyet.
Stewards and police moved in to protect Poyet and the majority of the crowd were streaming towards the exit by the 44th minute as Benteke netted.
The chaos enveloping Sunderland was summed up when they played several minutes at the start of the second half down to 10 men after Seb Larsson emerged late from the dressing room.
“A day like today you need to analyse very carefully as it’s not acceptable. There is nobody to blame but ourselves,” Poyet said.
“When you are a fan and you see your team performing like we did in the first-half I would do the same.”
– Relegation mire –
Crystal Palace pushed QPR deeper into the relegation mire with a 3-1 victory over their London rivals at Selhurst Park.
Alan Pardew’s side swept into a three-goal lead by half-time thanks to strikes from Wilfried Zaha, James McArthur and Joel Ward.
Matt Phillips produced one of the goals of the season in the closing stages, but the winger’s brilliant drive, from at least 40 yards out, came too late to spark a QPR fightback.
QPR’s fourth successive Premier League loss extended their miserable run to nine defeats in their last 10 games, leaving the west Londoners third bottom and four points from safety.
Bottom of the table Leicester wasted a chance to improve their survival hopes as 10-man Hull held on for a 0-0 draw at the King Power Stadium.
Hull had to play the final 18 minutes with 10 men after midfielder Tom Huddlestone was sent off for a second booking following his foul on Jamie Vardy.
West Brom ground out a 1-0 win against Stoke at the Hawthorns, with the only goal in the 19th minute from Brown Ideye.
Later on Saturday, second-placed Manchester City will aim to close the gap on leaders Chelsea when they travel to Burnley.
Chelsea, currently five points clear, are in action at home to Southampton on Sunday.
Also on Sunday, Manchester United host Tottenham and Everton face Newcastle, while Liverpool travel to Swansea on Monday.