The man was detained last night on the capital's north side.
32-Year-old Mr Byrne was lost his life after gunmen stormed the Regency Hotel in Drumcondra during a boxing weigh-in last February.
Two others were injured in the attack which is part of the long running and violent Kinahan-Hutch gangland feud.
A man in his 20s was arrested last night in the north Dublin area in relation to Mr Byrne's death.
He's being detained at Ballymun Garda Station under section 50 of the Criminal Justice Act – he can be held for up to seven days.
A second man was arrested in the operation last night on suspicion of dangerous driving.
