The commander said the 30,000 US reinforcements would "provide us the ability to reverse insurgent momentum and deny the Taliban the access to the population they require to survive".
He said he did not think he would need to ask for any more troops in a year's time, but would not hesitate to recommend more if circumstances changed.
The US ambassador to Afghanistan, Karl Eikenberry, who questioned the troop build-up during White House deliberations last month, also endorsed the new approach as "the best path to stabilise Afghanistan".
Mr Eikenberry agreed with Gen McChrystal that Bin Laden was key to that process.
He said it was "important to the American people - indeed, the people of the world - that one day Osama Bin Laden is either captured or killed, brought to justice".
The new battle plan includes an 18-month timeline before the first US troops would begin to come home.
Hours before the panel convened, Mr Gates held talks with Afghan President Hamid Karzai in the capital, Kabul.
Eight years after 9/11, Osama Bin Laden's whereabouts remain unknown
Speaking at a joint news conference afterwards, President Karzai warned that it would take 15 years before Afghanistan was able to pay for the cost of its own security forces, which the US wants to quadruple in size to 400,000 troops by 2013.
"We hope that the international community and the United States, as our first ally, will help Afghanistan reach the ability to sustain a force," he said.
For his part, Mr Karzai said he hoped the US and the international community would continue funding them, adding the US would not abandon Afghanistan.
The two countries would need to be long-term partners, he said.
The defence secretary said Mr Karzai needed to take a tougher line on corruption, but added that many ministers were competent and did not need to be replaced when a new cabinet is announced in the coming days.
Mr Karzai said he was committed to doing so and that he would inform parliament of the names of a number of proposed ministers.
Both men then agreed that it was a priority to strengthen the Afghan security forces in order to help international troops tackle insurgents.
But Mr Karzai was also cautiously optimistic that his country would be able to begin taking over responsibility for security in some "critical" parts of the country within two years, before taking charge nationwide in five years' time.
The president later condemned what his office said was the killing of six civilians in an overnight operation by Nato-led forces in the eastern province of Laghman.
Robert Gates: "We know that you prefer to have Afghans protecting Afghans"
Residents have protested against the reported civilian deaths, which they and provincial officials say number 12.
The Nato-led International Security Assistance Force said its troops killed seven militants and detained another four after coming under hostile fire while pursuing a member of the Taliban responsible for suicide bombings in the area.
Meanwhile, in a sign of the country's security difficulties, there were reports on Tuesday that Afghan officers had opened fire during a protest by villagers over the deaths of civilians, which they say occurred during a Nato operation.
According to one report, the Afghan soldiers fired into the air, but at least one person was killed.
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