The men, who were not named, were arrested at an address in west London as part of a pre-planned, intelligence-led investigation by the force´s Counter Terrorism Command.
One of the men, aged 19, was arrested on suspicion of preparing terrorist acts.
The other, aged 20, was arrested on suspicion of funding terrorism and failure to disclose information regarding a terrorist act.
He was also arrested on suspicion of preparing terrorist acts under a separate investigation by the South East Counter Terrorism Unit.
Officers were searching addresses and vehicles in west and southeast London and in the Thames Valley area.
Both men, who are from London, remain in police custody.
The current terrorist threat level in Britain is considered severe, meaning that an attack is highly likely.