Simpson was wounded while travelling with a convoy of US special forces and Kurdish fighters when they were mistakenly attacked by an American aircraft in the latest "blue-on-blue" incident.
Bloom died last night and NBC said in a statement on its website that his death was not combat related. It said he succumbed to a pulmonary embolism.
Bloom was co-anchor of the weekend editions of 'Today' and had previously covered a number of major news stories for NBC, including Israel and the violence in the Middle East, the war on terror in the US since 9/11. In Iraq, Bloom had been embedded with the US Third Infantry Division.
He was the second American journalist to die in Iraq. On Thursday night, Michael Kelly, Washington Post columnist and Atlantic Monthly editor-at-large, became the first American journalist to die in the conflict.
Kelly, 46, died along with a soldier from the US Army's Third Infantry Division when their Humvee vehicle went into a canal.
The death toll of journalists killed has now risen to six in 18 days of conflict. It is by far and away the highest number killed in such a short period of time covering any war.
Last week, BBC cameraman Kaveh Golestan was killed after stepping on a landmine in Northern Iraq and his producer, Stuart Hughes, was injured.
Channel 4 journalist Gaby Rado fell to his death from a hotel roof in the northern Iraqi town of Sulaymaniyah; ITN's Terry Lloyd died in a suspected friendly fire incident near Basra; and Australian Broadcasting Corporation cameraman Paul Moran was killed by a car bomb in northern Iraq.
Simpson was travelling as part of a convoy of vehicles that was attacked by a US warplane, thought to be a A-10 Thunderbolt tank buster, which was also responsible for an incident where two British soldiers from the Household Cavalry were killed when their Scimitar light reconnaissance tanks were destroyed by an A-10.
According to BBC reports, at least 10 people were killed, including Kamaran Abdurazaq Muhamed, a Kurdish translator working for the BBC.
In an incident echoing his "liberating" Kabul during the war in Afghanistan in 2001, Simpson broadcast live by satellite telephone on BBC News 24 only moments after the friendly fire incident while cars still burnt.
While broadcasting, Simpson at one stage thinks that an American soldier is trying to stop him when, in fact, it turned out to be an American medic attempting to treat his wound.
On air, he told viewers: "Well, it's a bit of a disaster... I was in a convoy of eight or 10 cars in northern Iraq coming up to a place that has just recently been captured. American special forces in a truck -- two trucks I think -- beside them, plus a very senior figure..." [brother of Massoud Barzani, leader of the Kurdistan Democratic Party]
Simpson to US soldier: "Shut up. I'm broadcasting! Oh yes, I'm fine -- am I bleeding?"
US soldier: "Yes, you've got a cut."
Simpson: "I thought you were going to stop me. I think I've just got a bit of shrapnel in the leg, that's all. OK, I will -- thanks a lot.
"That was one of the American special forces medics -- I thought he was going to try to stop me reporting."
Simpson told viewers that he saw the bomb drop right beside the convoy just 10 or 12 feet away. He described it as a "scene from hell" with vehicles on fire and dead bodies burning all around.
"I am sorry to be so excitable. I am bleeding through the ear and everything but that is absolutely the case. I saw this American convoy, and they bombed it," Simpson said.
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