A hat-trick from Glenn Ferguson saw Linfield beat their Big Two rivals in the CIS Cup final at Windsor Park.
The striker opened his account with a backpost header from Tim Mouncey's right-wing cross on three minutes.
Elliott Morris saved Jim Ervin's 20th minute penalty after the keeper pushed over Peter Thompson in the area.
Ferguson stroked the ball into an empty net after a defensive blunder on 48 and completed his hat-trick with a header from Pat McShane's fine cross after 75.
Ferguson's opener rocked the holders back on their heels straight away and soon after, Thompson had a good sight of goal but hooked the ball wide.
Darren Lockhart and Shaun Holmes had half-chances for Roy Coyle's side before Morris kept the Blues at bay by diving to keep out Ervin's spot-kick.
Alan Mannus tipped over a Gary Browne snaphot five minutes before the break while, at the other end, Michael Gault saw his left-foot shot saved by Morris.
Two minutes after the interval, Mouncey's dipping 20-yard free-kick rebounded off the Glentoran crossbar, but David Jeffrey's side soon extended their lead.
Stephen Parkhouse's misplaced pass fell to Thompson and he squared the ball to his strike partner Ferguson who found the unguarded net.
Browne had two further chances to bring his side into the match but his 53rd minute header was tipped over by Mannus and on 61 minutes, his low shot went just wide of the target.
Ferguson shot over the bar when well placed before completing his hat-trick by converting McShane's pinpoint delivery from the left wing.
Glentoran: Morris, Nixon, Simpson, McGibbon, Glendinning, McCann, Melaugh, Lockhart, Holmes, Browne, Morgan.
Linfield: Mannus, Ervin, McShane, Bailie, Murphy, Mouncey, Gault, McAreavey, Kearney, Thompson, Ferguson.
Referee: Michael Ross (Carrickfergus)