External Affairs Minister Salman Khurshid said that India had assured Italy that if convicted, the marines will not face the death penalty because this is not a "rarest of the rare" case. (Read: Salman Khurshid's statement in Parliament)
India and Italy have an agreement under which sentenced prisoners can serve jail time in their home countries.
Like earlier, the marines will not be under arrest during the trial. They will stay at the Italian embassy in Delhi and will need to report to a local police station once a week.
The marines flew to Delhi on an Italian air force plane. They were accompanied by Italian deputy foreign minister Staffan de Mistura.
India has reportedly promised Rome that a fast-track court will be commissioned in Delhi to handle the trial.
The Prime Minister, who had warned Italy of "consequences", said today he is "happy that the integrity and dignity of the Indian judicial process has been upheld".
On March 11, the Italian government said the marines would not return to face trial for shooting a pair of fishermen from Kerala at sea last year. The marines say they mistook the fishermen for pirates.
The Supreme Court was furious with the decision since it had permitted the naval officers to spend a month at home to celebrate Easter and vote in the national election.
The court banned the Italian envoy, Daniele Mancini, from leaving India because he had personally mediated the marines' release and had assured the judges in writing that the men would honour their commitment to stand trial.
But the European Union agreed with Italy's contention that this violates international laws which guarantee the freedom of movement of diplomats and prohibit their arrest or detention.