As of the end of July 2010, he is ranked 37th in the Rolex World Rankings - Ireland's number 4.
2004 Olympic Games
Riding his horse, Waterford Crystal, he became an instant national hero, being the only Irish medalist that year. However, on 8 October 2004, it emerged that Waterford Crystal had tested positive for a prohibited substance. Components of the 'B' sample were stolen, as were documents from the Irish Equestrian Federation offices. However, the B blood sample also tested positive for prohibited, but not performance-enhancing, substances, which had been prescribed to the horse some time earlier.
The Federation Equestre Internationale (FEI) ruled that O'Connor must be stripped of his medal and he also received a three month ban from competition. On 10 June 2005, O'Connor's solicitor filed an official waiver of appeal in the FEI which made the Judicial Committee’s decision official. O'Connor lost his gold medal and the Irish Show Jumping Team was disqualified by the Olympic Board. The individual showjumping gold medal went to Brazilian Rodrigo Pessoa and the Irish team's seventh place was inherited by the Italians.
In December O'Connor was invited to jump at Olympia, London, finishing, on Rancorrado, 2nd in the World Cup Qualifier, his highest placing in a Qualifier to date. The next night he won the Grand Prix, and this in turn secured him the Leading Rider of the Show.
O'Connor won the Basel Grand Prix with Rancorrado in January.
In February, Cian was selected as part of the Irish Team to compete in the Nations Cup of Dubai with Rancorrado; the team finished 7th of the 11 teams.
During a break in international competition, he jumped in the second leg of Ireland's 'HSI Chippison Grand Prix Tour' in Cavan Equestrian Centre. He took first and second place with Complete and Splendor respectively. He then took the 4th leg of the 'HSI Chippison Grand Prix Tour' with Complete at Kill International Equestrian Centre on 14 March and his 3rd 'HSI Chippison Grand Prix' Title in Kilkenny, again with Complete. He also took 6th spot in Kilkenny with a double clear from his new horse - K Club Lady.
Cian's return to International competition came at the CSI3* in Lummen, Belgium. Here, he picked up a win in a 1m40 speed class with Splendor. His new ride - K Club Lady also had a good week, she was clear in all of her classes, including a double clear in the 1m50 World Equestrian Games qualifier to finish 3rd.
Next on the calendar was Valencia for the opening leg of the Global Champions Tour. On the opening day, Cian and K Club Lady jumped one of only 6 double clears in the 1m50 class to finish 4th - just 1.65 seconds off the winner. The class was won by the Olympic Champion Eric Lamaze on his Olympic horse - Hickstead.
At the end of May, O'Connor travelled to the CSIO5* Rome as part of the squad for the second leg of the Meydan Nations Cup series. On Day 2, he steered Complete to third place in the 1m40 jump-off class - just 0.23 of a second behind the winner. O'Connor was third to jump for the Irish team that finished equal 3rd in the Nations Cup on 12 faults: Cameron Hanley (Southwind VDL) - (8)/4; Darragh Kenny (Obelix) - 4/(8); Cian O'Connor (K Club Lady) - 4/0; Billy Twomey (Tinka's Serenade) - 0/4. Complete then followed up on his earlier placing (day 2) by coming 4th in the 1m40 speed class on the 3rd day.
O'Connor and K Club Lady then headed to the CSIO5* of St. Gallen, Switzerland - again as part of the Irish Team in the third leg of the Meydan Nations Cup Series. The team finished 4th in a very high faulting competition on 19 faults: Shane Breen (Carmena Z) 5/5; Darragh Kenny (Obelix) 5/(16); Cian O'Connor (K Club Lady) 9/4; Billy Twomey (Je T'aime Flamenco) (9)/0. O'Connor then topped off the show by finished second on his relatively new mare K Club Lady in the 300,000 Grand Prix. He was one of only 2 double clears, and bagged 60,000 for his effort.
Global Champions Tour of Estoril, Portugal: In a GCT Grand Prix that only saw six combinations through the first two rounds to the jump-off, O'Connor and K Club Lady had four faults in Round B to finish 8th and collect €6,000.
O'Connor travelled as part of the Irish team to the World Equestrian Festival at the CSIO5* Aachen, Germany. On day 2, he and Splendor finished 6th of 52 in the jump-off class to earn €1,000. In the 6th leg of the Meydan FEI Nations Cup on Thursday, the Irish team finished on a 4 fault score to win: Billy Twomey (Tinka's Serenade) 4/0; Dermott Lennon (Hallmark Elite) 0/0; Cian O'Connor (K Club Lady) 0/0; Denis Lynch (Lantinus) (4)/(NS). On Saturday, he and Splendor finished 9th in the 'Aachen Munchener' jump-off class. The pair then finished-off the week by coming 3rd in a one round class on Sunday.
The final of the Meydan FEI Nations Cup was next for Cian. This was held on 'home territory' at the RDS Showgrounds in Dublin, Ireland. In the Nations Cup on Friday, Ireland finished joint 2nd on 20 faults with the USA: Billy Twomey (Tinka's Serenade) 0/4; Dermott Lennon (Hallmark Elite) (12)/(8); Cian O'Connor (K Club Lady) 8/0; Denis Lynch (Nabab's Son) 8/0. This result secured Ireland 4th place in the overall standings. On Saturday, O'Connor (and Noctambule Courcelle) shared the honours with Pablo Barrios in the Puissance. The pair both cleared 2m10 in the 4th rouned but neither could manage the 2m15 of the final round.
Family and personal life
On 19 June 2002, Cian's then-girlfriend Hazel O'Callaghan, daughter of property tycoon Owen O'Callaghan, was fatally injured while trying to unload a horse from a trailer.
- Meydan FEI Nations Cup of Aachen, Germany, (K Club Lady)
- 2nd, Grand Prix - CSIO5*, St. Gallen, Switzerland, (K Club Lady)
- Grand Prix - Basel CSI4*, Basel, Switzerland, (Rancorrado)
- Grand Prix - Olympia CSI5*-W, London, United Kingdom, (Rancorrado) - Also Leading Rider of the Show
- 2nd, Rolex FEI World Cup Qualifier - Olympia CSI5*-W, London, United Kingdom, (Rancorrado) - Also Leading Rider of the Show
- FEI World Cup Qualifier - CSI3*-W Tripoli, Libya, (Irish Independent Echo Beach)
- 3rd, Rolex FEI World Cup Qualifier - Leipzig CSI5*-W, Germany, (Rancorrado)
- 2nd, Grand Prix - CSI5*-W Geneva, Switzerland, (Complete)
- Grand Prix - CSI4* Chantilly, France, (Rancorrado)
- Nations Cup - CSIO5* Lummen, Belgium, (Irish Independent Echo Beach)
- Nations Cup - CSIO4* Poznan, Poland, (Complete)
- 2nd, Grand Prix - CSI3* Frankfurt, Germany, (Waterford Crystal)
- Ireland at the 2004 Summer Olympics
- List of Irish sports people