rvis on 40 minutes.However, German forward Podolski quickly levelled before half-time, with Giroud's superb control and close-range finish putting them in front on 55 minutes.
Another powerful strike from Podolski with 13 minutes left secured all three points which saw Arsene Wenger's side move back up above Everton, who host Crystal Palace on Wednesday night.
Wenger was impressed with the composure of Giroud's finish, when he held off both Winston Reid and Andy Carroll to take down a high ball from Thomas Vermaelen on his left foot before rolling it between the goalkeeper's legs with his right.
"It was a perfect first touch," said Wenger.
"You need that if you want to score the goal
What I like is that he used his upper body first to make some space and, despite that, he managed to have a great first touch and after that he finished well."
Giroud paid his own tribute to the victims of Hillsborough when he kissed the black armband and looked to the heavens as the Arsenal players celebrated.
"Olivier is a great guy with a great mentality," said Wenger of the France forward whose personal life put him under media scrutiny earlier in the season.
"He has gone through a difficult period, as you know, and I think it affected his game for a while and his confidence.
"You could see that he was refreshed tonight and that he was up for it.
"At half-time he came in, he was very, very down because he missed a great chance in the first half, but he responded very well in the second half because he's mentally a strong guy."
Wenger hopes the manner of the performance can lift his squad for the run-in.
He said: "Saturday and tonight improves the confidence of the team, but we know we have one advantage - the picture is very clear in front of us.
"We know we have to win our games and hope that Everton will slip up somewhere, but let's focus on our job and not look too much at Everton.
"If we need that we will see when we need it, but at the moment we can only do it if we win our games, so let's focus on that."
West Ham manager Sam Allardyce felt his side had been the architects of their own downfall after getting a foothold in the match.
"We shoot ourselves in the foot," he said.
"Doing so well to get the first goal, we then could not get into half-time 1-0 up, which was a big disappointment.
"We were then looking comfortable and the second goal sickened me off because the performance meant nothing after that.
"All of our hard work has been wasted."
Jarvis was caught by Bacary Sagna as he ran into the Arsenal penalty area early in the match, for which Wenger said he was "grateful".
Allardyce believes his player's "honesty" got no reward.
"For years now, the facts are that when you stay on your feet, referees do not give penalties," the Irons boss said.
"For honesty, there is no reward, so what do I do?
"A foul is a foul, it does not matter if you go down or stay on your feet.
"We get slaughtered for diving or being dishonest, but when someone is honest and does not get what you should get...so then you should go down and make the referee's mind up for him.
"But we still got in front after that, so from then on it is us who have let ourselves down."
Source : PA
Source: PA