Pat Lam's men made sure of a home semi-final thanks to a hard-fought win over reigning champions Glasgow Warriors.
Gregor Townsend's men dominated the early exchanges but trailed 7-0 at the break thanks to Bundee Aki's drive over at the foot of the posts.
Gordon Reid's try levelled things up early in the second half and while the game stood a 7-7 for some time, Warriors were dreaming of a home semi-final.
However, Tiernan O'Halloran touched down to give Lam's side the 14-7 victory and book a replay against Warriors at the Sportsground in two weeks' time.
2. Glasgow run comes to crashing halt
After nine Guinness PRO12 games unbeaten Warriors failed to make double figures and subsequently lost home advantage in the semi-finals.
The reigning champions went into Round 22 at the head of the table but the loss to Connacht meant they slipped to third and face another trip across the Irish Sea in a fortnight.
In 2015 Warriors topped the end-of-season table and edged past Ulster in a tight semi-final at Scotstoun but if they are to repeat their success this year they will have to do it the hard way.
3. Munster end season with Champions Cup rugby
After losing to Cardiff Blues, Leinster and Connacht in the closing weeks of the season to end their hopes of a semi-final spot, Anthony Foley's men won their final two games to salvage a Champions Cup place from the campaign.
In Round 21 they beat Edinburgh 27-19 and they followed that result up with a final day victory over fifth-placed Scarlets to ensure the Red Army will have elite European rugby to look forward to next season.
A try apiece from Ronan O'Mahony, CJ Stander and Franciss Saili, as well as a double from Rory Scannell, was enough to ease past Scarlets 31-15, who could only muster five Steve Shingler penalties.
4. Leinster breeze to the top of the table
Leinster regained top spot in the Guinness PRO12 table when it really mattered with an eight-try romp against Benetton Treviso at the RDS Arena.
The inter-provincial win over rivals Munster in Round 19 was enough to put Leinster top of the pile but Warriors had taken over the mantle in the last two weeks, only for Leo Cullen's men to take advantage of their final day slip-up, reclaim the league lead and with it a home semi-final.
Ulster will head to the RDS Arena in a fortnight for the crunch tie and having each won their respective home tie against the opposition during the regular season, it looks set to be another close match.
5. Ulster secure last semi-final spot
With Scarlets losing, Ulster's position in the semi-finals was secured no matter their result, but they put on a show nonetheless with a bonus-point win in Wales.
The Ulstermen ran in six tries to down Ospreys 46-26 in a rip-roaring end-of-season encounter with Paddy Jackson scoring 21 points for Les Kiss' side.
Ospreys racked up four tries of their own but it was not enough to stop the visitors booking their post-season place for the fourth season in a row.
6. Four Irish provinces make Champions Cup
Munster, Ulster and Leinster all represented Ireland in Europe's elite club competition this season but Connacht have now joined the party to make it a full complement of Irish sides in the tournament next season.
No Irish side made it out of the Pool stage of this year's competition, with Ulster missing out by a single point in the race for the best Pool runners-up.
However, with an extra side competing next term, Irish rugby will be hopeful of representation in the knockout stages of the tournament.
7. Zebre pip Treviso to Italian Champions Cup spot
With a single Champions Cup spot available to Italian sides in next year's competition, the race for the coveted spot went down to the final Guinness Pro12 round.
Zebre's stunning 47-22 victory over Newport Gwent Dragons at the Stadio Sergio Lanfranchi leapfrogged them over Treviso, who were downed by Leinster, to move off the bottom of the table and book their place against Europe's best next season.
The win snapped a ten-game losing streak for Zebre and was their fifth victory of the season, two ahead of their Italian rivals.
8. Welsh regions stuck in mid-table
For only the second time in seven years there will be no Welsh representation in the Celtic League semi-finals.
Scarlets' loss, coupled with an easy win for Ulster, meant the sole Welsh side in with a hope of semi-final qualification, saw those hopes dashed on the final day and finished in fifth place.
Ospreys, who have four Celtic League titles to their name, finished the season in eighth place with Cardiff Blues one spot above them and Dragons the lowest Welsh side in tenth.
9. Marco Bortolami signs off in style
The Italian talisman retired from his playing career in style with a man-of-the-match performance as Zebre beat Dragons to qualify for the Champions Cup.
Bortolami, 35, who has 112 Italy caps to his name and has played in the Celtic League for Aironi and Zebre, hung up his boots after the win and is now looking forward to coaching at the Parma club.
The lock led his side out before the game, accompanied by his daughter, and shone in his final appearance as Gianluca Guidi's men gave him a send-off to remember.
10. Mixed fortunes for Scottish sides
Edinburgh Rugby failed to match their best finish in six years as a final day defeat to Cardiff Blues saw them drop one place to ninth.
In contrast, reigning champions Glasgow Warriors will be appearing in their fifth semi-final in a row in a fortnight.
Edinburgh went into Round 22 with a slim chance of a spot in next season's Champions Cup but despite missing out, head coach Alan Solomons is already looking forward to next season.
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