Prominent democracy activist Kyaw Min Yu -- better known as "Jimmy" -- received the same sentence from the military tribunal, the statement added, carrying pictures of both men.
Their sentences were also read out on state media's nightly news.
The junta has sentenced dozens of anti-coup activists to death as part of its crackdown on dissent but Myanmar has not carried out an execution for decades.
Phyo Zeyar Thaw -- whose real name is Maung Kyaw -- was arrested at an apartment in the commercial hub Yangon following a "tip-off and cooperation from dutiful citizens," the junta's information team said.
He had been accused of orchestrating several attacks on regime forces, including the brazen shooting on a commuter train in Yangon in August that killed five policemen.
He was elected to parliament from Suu Kyi's National League for Democracy party in the 2015 elections that ushered in a transition to civilian rule.
Kyaw Min Yu, who rose to prominence during Myanmar's 1988 student uprising has been arrested in an overnight raid in October.
Part of the so-called 88 Generation movement that challenged Myanmar's previous military government, the junta issued an arrest warrant for him last year, alleging he had incited unrest with his social media posts.
Suu Kyi is facing a raft of criminal and corruption charges -- including violating the country's official secrets laws -- and if convicted of all of them could face sentences tallying more than 100 years of prison.
Before the coup, Suu Kyi was on the cusp of beginning another five-year term as the country's de facto leader after the National League for Democracy won a landslide in November 2020 polls.