The Cheetahs booked a place in the Super Rugby play offs and ended the Blues chances of progressing with a 34-13 Super Rugby victory in Bloemfontein.
The Cheetahs have a bye next weekend so they are gauranteed another four points - and a rest week ahead of the knock out stage.
The Cheetahs victory is a blow for their fellow South African teams the Sharks and the Stormers as neither can overtake the Bloemfontein franchise so their seasons are also effectively over as far as the title is concerned.
Cheetahs fly-half Riaan Smit put the Bloemfontein-based franchise ahead after two minutes with the first of five successful penalty kicks, but the Blues hit back through a clever try from scrum-half Jamison Gibson-Park.
Fly-half Baden Kerr converted to give the Blues a four-point advantage before a 12,000 Free State Stadium crowd in a match the visitors had to win to keep alive their own play-off hopes.
Another Smit penalty cut the deficit to a single point and when No. 8 Philip van der Walt barged over beside the post after a scrum, the Cheetahs had a lead they never surrendered.
They turned over 19-10 ahead in a tense, error-strewn match, and sealed success with a couple of late tries from two replacements, scrum-half Sarel Pretorius and lock Boom Prinsloo.
Smit contributed the other 19 points for the home side via two conversions and five penalties as the Cheetahs put their poor recent form behind them to ensure finishing at least sixth.
A bye in the final round next weekend will give the Cheetahs four additional points and lift them to 54, and they will rise one place to fifth if the Reds return pointless from a visit to fellow Australians, the Waratahs.
Cheetahs' victory not only eliminated three-time champions the Blues, but also South African sides the Stormers and the Sharks.
"I am very proud of my team, although we left a few tries out there," said Cheetahs hooker and skipper Adriaan Strauss.
"We stuck to instructions this evening and each player focused on his task.
"No one gave us a chance of finishing among the top six teams when the season kicked off last February, but I always believed we could do it. We will take Sunday off and then start training for the knock-out stage."
Blues skipper and recently retired All Blacks lock Ali Williams lavished praise on the Cheetahs, who completed a 16-match league schedule with 10 victories and six defeats after starting the season with two losses.
"We were outclassed - they strangled the life out of us and good luck to them in the rest of the competition. The Cheetahs play rugby with tremendous passion."
In a match of too many knock-ons, reset scrums and scrappy exchanges, a major surprise was the failure of usually dynamic Blues left-wing Rene Ranger to make an impact.
His lone chance to score came seven minutes after half-time when he collected a Willie le Roux chip inside the Blues' 22 and burst clear only to be superbly tackled by left-wing Raymond Rhule in Cheetahs' territory.
Baden Kerr, part of a second-choice starting half-back partnership with Gibson-Park as Chris Noakes and Piri Weepu were injured, also kicked two penalties for the Auckland outfit.
Final Score Cheetahs 34 (19) Blues 13 (10)
Tries - P. van der Walt, S. Pretorius, B.Prinsloo
Pen - R. Smit 5
Con - R.Smit 2
Tries - J.Gibson-Park
Pen - B.Kerr 2
Con - B.Kerr
Referee: Jaco Peyper
Assistant Ref 1:Ben Crouse
Assistant Ref 2:Francois de Bruin
TMO : Gerrie Coetzee
15. Hennie Daniller, 14.Willie le Roux, 13.Johann Sadie, 12. Robert Ebersohn (VC) , 11.Raymond Rhule , 10. Riaan Smit, 9. Piet van Zyl, 8. Philip van der Walt, 7.Lappies Labuschagne, 6. Heinrich Brussow, 5. Ligtoring Landman, 4. Lodewyk de Jager, 3. Lourens Adriaanse, 2. Adriaan Strauss (C), 1.Coenie Oosthuizen.
Replacements: 16. Ryno Barnes, 17. Trevor Nyakane, 18.Waltie Vermeulen, 19. Boom Prinsloo, 20.Sarel Pretorius, 21. Elgar Watts, 22.Ryno Benjamin
15. Charles Piutau,14. Frank Halai,13. Jackson Willison,12. Francis Saili,11. Rene Ranger,10. Baden Kerr,9. Jamison Gibson-Park,8. Peter Saili,7. Luke Braid,6. Steven Luatua,5. Ali Williams (C),4. Anthony Boric,3. Angus Ta’avao,2. James Parsons,1. Sam Prattley
Reserves:16. Keven Mealamu,17. Ofa Tu’ungafasi,18. Culum Retallick,19. Brendon O’Connor,20. Wayne Ngaluafe,21. Marty McKenzie,22. George Moala