Marcel Siem nimmt 2012 an den folgenden Turnieren teil:
| Turnier | Datum | Platzierung | gewonnenes Preisgeld | Sieger (Titelverteidiger) |
|---|---|---|---|---|
| Abu Dhabi HSCBC Golf Championship | 26.1. - 29.1. | T35 | € 14.367 | Robert Rock |
| Commercialbank Qatar Masters | 2.2. - 5.2. | T12 | € 27.542 | Paul Lawrie |
| Omega Dubai Desert Classic | 9.2. - 12.2. | 4 | € 94.661 | Rafael Cabrera-Bello |
| Avantha Masters | 16.2. - 19.2. | T2 | € 156.340 | Jbe Kruger |
| Open de Andalucia Costa del Sol | 15.3. - 18.3. | T17 | € 12.933 | Julien Quesne |
| Trophée Hassan II | 5.4. - 8.4. | T52 | € 5.550 | Bubba Watson |
| Maybank Malaysian Open | 12.4. - 15.4. | T29 | € 16.522 | Louis Oosthuizen |
| Volvo China Open | 19.4. - 22.4. | T71 (Cut) | - | Branden Grace |
| Reale Seguros Open de España | 3.5. - 6.5. | T12 | € 31.650 | Francesco Molinari |
| BMW PGA Championship | 24.5. - 27.5. | T7 | € 116.100 | Luke Donald |
| ISPS Handa Wales Open | 31.5. - 3.6. | T33 | € 17.555 | Thongchai Jaidee |
| BMW International Open | 21.6. - 24.6. | T6 | € 65.000 | Danny Willett |
| The Irish Open | 28.6. - 1.7. | 57 | € 6.200.00 | Jamie Donaldson |
| Alstom Open de France | 5.7. - 8.7. | 1 | € 525.000 | Marcel Siem |
| Aberdeen Asset Management Scottish Open | 12.7. - 15.7. | T29 | € 25.844 | Jeev Milkah Singh |
| The OPEN Championship | 19.7. - 22.7. | MC | - | Ernie Els |
| WGC Bridgestone Invitational | 02.8. - 05.8. | 60 | $44.500 | Keegan Bradley |
| PGA Championship | 9.8. - 12.8. | T36 | $34.750 | Rory McIlroy |
| Johnnie Walker Championship at Gleneagles | 02.8. - 05.8. | T19 | € 20.153 | Paul Lawrie |
| Omega European Masters | 30.8. - 2.9. | T14 | € 29.610 | Richie Ramsay |
| Alfred Dunhill Links Championship | 4.10. - 7.10. | MC | - | Branden Grace |
| Portugal Masters | 11.10. - 14.10. | 68 | € 4.838 | Shane Lawry |
| BMW Masters | 25.10. - 28.10. | T51 | € 19.727 | Peter Hanson |
| WGC HSBC Champions | 01.11. - 04.11. | T11 | $ 98.000 | Ian Poulter |
| Singapore Open | 08.11. - 11.11. | MC | - | Matteo Manassero |
| DP World Tour Championship | 22.11. - 25.11. | T42 | € 34.993 | Rory McIlroy |
