The 1,044-passenger Soctia Prince docked in Colombo harbour after setting off from the southern Indian port of Tuticorin on Monday, a port official said.
"This is the first time that that the two destinations are linked by a passenger ferry service," the official said, adding that the Indian operators of the vessel planned a twice-weekly service between Colombo and Tuticorin.
The ferry takes about 14 hours to make the journey across the Palk Straits, officials said, adding that Sri Lankan authorities would launch another boat to increase passenger capacity on the route.
A much shorter boat ride between the south Indian town of Rameswaram and Sri Lanka's north-western town of Talaimannar came to halt in 1983 when the island's Tamil separatist conflict escalated into a full-blown guerrilla war.
However, Sri Lankan troops crushed Tamil Tiger rebels in May 2009, ending the war in a military campaign which sparked allegations of war crimes.
The ferry is being launched at a time when the South Indian state of Tamil Nadu has asked New Delhi to impose economic sanctions against Sri Lanka over its alleged killing of Tamil civilians during the crackdown.
The ethnic Tamils in Tamil Nadu share close cultural and religious links with Sri Lanka's Tamil minority.
Copyright APP (Associated Press of Pakistan), 2011
Copyright AFP (Agence France-Presse), 2011