The 26 are all listed as members or sympathisers of the Tamil Tigers rebel group in Sri Lanka.
They were found guilty of involvement in Mr Gandhi's assassination earlier on Wednesday.
After the guilty verdict, a senior police official D R Karthikeyan said: "Truth has prevailed. The nation stands vindicated."
The leader of the Liberation Tigers of Tamil Eelam, Velupillai Prabhakaran, and his top two aides, were found guilty of the murder in absentia.
![[ image: width=150]](/olmedia/50000/images/_51541_gandhiindex.jpg)
The investigation into the suicide bombing at an election rally had originally implicated 41 people but 12 had since taken their own lives.
The minimum sentence for the 26 people convicted of conspiracy in the Tamil Nadu court by Judge V Navaneetham would have been five years in jail.
Although Indian law allows the death penalty, it is rarely used.
The Tamil Tigers rebel group in Sri Lanka has always denied any involvement in Mr Gandhi's assassination.
Mr Prabhakaran remains in Sri Lanka. Despite India's request to Colombo to extradite the rebel leader in June 1995, he has eluded capture.
A judge's probe of the Gandhi assassination brought down the government last year, when it indicted a party in the ruling coalition for "tacit support" for the Tamil Tigers.
Mr Gandhi's Congress party responded by withdrawing its crucial support for the ruling United Front coalition, triggering India's second elections in as many years.
Indian officials say the separatist Tamil Tigers decided to kill Mr Gandhi in revenge for the Indian army's involvement in Sri Lanka.
Indian troops sent in to disarm the guerrillas under a 1987 accord with the Sri Lankan government ended up fighting Prabhakaran's men.
They were pulled out in 1990, after Mr Gandhi lost power.
Mr Gandhi was killed by a suicide bomber in 1991 during an election rally.
India's ruling dynasty
(12 Jan 98 | Special Report)
Has justice been done?
(28 Jan 98 | World)
Rajiv Gandhi's widow joins politics
(29 Dec 97 | World)
Indian Parliament suspended after uproar
(24 Nov 97 | World)
New light on the killing of Rajiv Gandhi
(18 Nov 97 | Special Report)
Rajiv Gandhi Foundation
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