A special court known as the Permanent Trial-at-Bar found the pair guilty on multiple charges, including failing to prevent the attacks despite prior intelligence warnings, criminal dereliction of duty, murder and attempted murder, local broadcaster Ada Derana reported.
Lawyers for Fernando, formerly the secretary to the ministry of defence, and Jayasundara were not immediately available for comment.
Sri Lanka retains the death penalty but has observed a long-standing de facto moratorium on executions, with death sentences typically commuted to life imprisonment.
The two former officials were acquitted of the same charges by a three-judge High Court bench in 2022.
However, a fresh trial began in March after the Supreme Court ordered the case to be reheard.
President Anura Kumara Dissanayake, who was elected in 2024, has pledged to hold those responsible for wrongdoing to account.
The attacks on April 21, 2019, targeted three churches and three hotels.
The bombings, the deadliest in Sri Lanka's recent history, also injured about 500 people, many of them members of the island's Christian minority.
