Reports say the men, who worked with a private company in Qatar, were arrested last year on suspicion of spying.
Neither Qatar nor India have revealed the specific charges against them.
India’s external affairs ministry spokesperson Arindam Bagchi said India has “already filed an appeal” against the verdict.
The ministry added that it had consular access to the detainees on Tuesday.
The Indian government said last month it was “deeply shocked” and would take up the verdict with Qatari authorities.
The foreign ministrydescribes the men as employees of a private company called Al Dahra, but they have been widely reported to be former personnel of the Indian Navy. Last year, in parliament, foreign minister S Jaishankar described them as “ex-servicemen” of the country.
The families of some of the men have also confirmed their identities and background in the navy to local media.
Their arrest in August last year made front-page headlines in India, but there has been little confirmed information about the charges against them.
According to The Hindu newspaper, the men were allegedly accused of “breaching sensitive secrets”, but neither governments have confirmed this.
Experts say the recent diplomatic tensions could impact relations between the two countries. In December, Mr Jaishankar told parliament the government was in constant touch with Qatar over the “very sensitive case”.
Millions of Indians live in the Gulf, with tens of thousands of them working in semi-skilled and unskilled low-income jobs.
These migrant workers have played a key role in building the economies of Gulf Arab states and also form an important source of remittances for India.
Source : BBC