The Olympic bronze medallist beat the Kildare man 20-9 in Dublin's National Stadium to put himself in a great position for the European and World Championships later this year.
Pelan was unable to cope with Conlan's superior speed and footwork which saw the Belfast man win all three rounds.
Fellow Belfast fighters Sean McComb and Tommy McCarthy also secured Irish titles.
Heaveyweight McCarthy, from the Oliver Plunkett club, stopped Jimmy Sweeney of Drimnagh in the third round of their match, while Holy Trinity boxer McComb won the lightweight title 19-7 over George Bates from Dublin's St Mary's club.
Michaela Walsh, also from Belfast, won her fourth featherweight title with a narrow 6-5 victory over Joanna Lambe from Monaghan.
London Olympic boxing champion Katie Taylor began her comeback on the night, which she hopes will bring her a second consecutive Olympic gold medal in 2016.
However, it was the end of the line for Ken Egan who called time on his illustrious career - which saw him win silver in the light-heavyweight division in Beijing and 10 national titles - after defeat to Joe Ward.