Clotarf secured the fourth playoff spot in Division 1 to earn themselves a semi final clash with league toppers Cork Con. Shannon squeezed ahead of Garryowen to earn the home advantage in the other semi final.
Meanwhile two Leinster clubs will be relegated. Greystones, promoted from Division 2 last season with Old Belvedere, and Lansdown, who lose out on points difference to Galwegians despite a gallant last day stand.
Ballymena 7-38 Dungannon
Dungannon saved their best performance of the league season to the final day as they staved off relegation at Eaton Park.
The Tyrone men ran in six tries against their Ulster rivals to maintain their Division One status.
Ballymena trailed by 18-0 at half-time with wind-backed 'Gannon's Richard McCarter and Andy Hughes both touching down.
The hosts cut the gap with a penalty try but further efforts from McCarter, Hughes, Derek Hall and John McGuckin saw 'Gannon get the required result.
Try: Penalty try; Con: Craig Woods
Tries: Richard McCarter 2, Andrew Hughes 2, Derek Hall, John McGuckin; Con: Richard McCarter; Pens: Richard McCarter 2
Clontarf 37-14 Galwegians
Clontarf booked their place in the Division One semi-finals with a facile win at Castle Avenue.
'Tarf kept hold of fourth place to set up a play-off trip to Cork Constitution on 3 May.
Backed by a huge wind, Andy Wood's side raced into a 37-0 half-time lead with centres Daragh O'Shea and Marc Hewitt sharing out four tries.
Winger John Cleary got two second half touchdowns for Galwegians and they proved crucial as the men from the west avoided relegation on scoring difference.
Tries: Daragh O'Shea 2, Marc Hewitt 2, Phil Howard; Cons: Daragh O'Shea 3; Pens: Daragh O'Shea 2
Tries: John Cleary 2; Cons: Peter Durcan 2
Garryowen 34-13 UCD
Garryowen finished third in the final Division One table to set up a mouthwatering semi-final trip to their Limerick neighbours Shannon.
Garryowen set a new club record for consecutive AIB League wins - this was their tenth - as they easily accounted for UCD.
The hosts led 13-3 at half-time with centre Conan Doyle collecting a 25th-minute try.
UCD did counter with tries from Michael Hastings and Andy Cummiskey, but efforts from Cillian O'Boyle, Damien Varley and Gerry Hurley saw Garryowen chalk up their bonus point.
Tries: Cillian O'Boyle, Conan Doyle, Damien Varley, Gerry Hurley; Cons: Conor Kilroy 4; Pens: Conor Kilroy 2
Tries: Michael Hastings, Andy Cummiskey; Pen: Killian Lett
Blackrock College 49-27 St Mary's College
Blackrock College ended the league campaign on a high with a comeback win over St Mary's College at Stradbrook.
But this victory was marred by injuries to 'Rock captain Des Dillon (dislocated elbow) and full-back Fionn Carr, who was taken to hospital with a suspected broken fibula.
Mary's made the early running - tries from Matt D'Arcy (2) and Mike Skelton helped them to a 19-16 interval lead.
But 'Rock came good with Kyle Tonetti, David Rowan and Paul Graham both finishing with two tries apiece.
Tries: Kyle Tonetti 2, David Rowan 2, Paul Graham 2; Cons: Fionn Carr 4, Ian Madigan; Pens: Fionn Carr 3
St Mary's College:
Tries: Matt D'Arcy 2, Mike Skelton, Frank Lynch; Cons: Frank Lynch 2; Pen: Frank Lynch
Cork Constitution 25-3 Dolphin
In the battle of Cork's top flight sides, Cork Constitution proved the stronger in a three-try win at Temple Hill.
Upwards of 4,000 spectators were present to witness the clubs' first ever AIB League clash at Temple Hill.
Dolphin opened the scoring with a Barry Keeshan penalty but a Tom Gleeson try and two Richie Lane penalties had Con 11-3 ahead at half-time.
Recently retired Munster winger John Kelly helped set up a try for Lane and Cronan Healy grabbed the clinching score.
Tries: Tom Gleeson, Richie Lane, Cronan Healy; Cons: Richie Lane 2; Pens: Richie Lane 2
Pen: Barry Keeshan
Old Belvedere 33-18 UL Bohemians
Old Belvedere rounded off their season in fine style with a five-try success over UL Bohemians at Anglesea Road.
The win was also notable as it saw 'Belvo crash through the 4000-point barrier in the all-time AIB League.
Early tries from Leinster's Richie Leyden and Eoin O'Malley had the hosts leading 14-6 at the break.
Bohs rallied with touchdowns from Ian Hanly and Ryan Hartigan. However, the Dubliners powered home with Leyden, Felix Jones (his sixth league try) and Eamonn Fitzgerald adding further scores.
Tries: Richie Leyden 2, Eoin O'Malley, Felix Jones, Eamonn Fitzgerald; Cons: Brian Collins 4
: Tries: Ian Hanly, Ryan Hartigan; Con: Fergal Lawlor; Pens: Fergal Lawlor 2
Shannon 38-5 GreystonesShannon strode confidently into the Division One semi-finals as they relegated Greystones at Coonagh this afternoon.
'Stones needed a shock final day win to stay in the top flight but Shannon, with a home semi-final draw in their sights, were in unforgiving mood.
The AIB Cup champions led 24-0 at half-time with Stephen Kelly (2) and Sean Cronin both touching down.
Further tries from Cronin and captain David Quinlan saw Shannon out of sight with Stuart Abbott grabbing a consolation score for 'Stones.
Tries: Sean Cronin 2, Sean Kelly 2, David Quinlan; Cons: David O'Donovan 5; Pen: David O'Donovan
Try: Stuart Abbott
Terenure College 20-27 Lansdowne
Lansdowne played their hearts out at Lakelands Park, doing everything possible to avoid a final day relegation.
But despite scoring a bonus point win over Terenure, Lansdowne will be playing Division Two rugby next season. They lost out on scoring difference in the table to Galwegians.
17-5 ahead at half-time, David Kearney scored two tries for Lansdowne, whose other efforts came from a penalty try and a Darren O'Reilly touchdown.
Terenure claimed a losing bonus point with late scores from Bertrand Guiry and Brian Blaney.
Tries: Mark Mahony, Bertrand Guiry, Brian Blaney; Con: David McAllister; Pen: David McAllister
Tries: David Kearney 2, Penalty try, Darren O'Reilly; Cons: Andy Geraghty 2; Pen: Andy Geraghty