The 31-year-old has made just one Premier League start for the Hammers since joining them from Marseille in the summer.
Rennes will become the sixth Ligue 1 side that Diarra has represented.
He has also enjoyed stints at Le Havre, Bastia, Lens, Lyon and Bordeaux.
Diarra, who has been capped 44 times by France at senior international level, is under contract at Upton Park until June 2015.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Liverpool | 12 | 10 | 1 | 1 | 24 | 8 | 16 | 31 |
| 2 | Manchester CityMan City | 12 | 7 | 2 | 3 | 22 | 17 | 5 | 23 |
| 3 | Chelsea | 12 | 6 | 4 | 2 | 23 | 14 | 9 | 22 |
| 4 | Arsenal | 12 | 6 | 4 | 2 | 21 | 12 | 9 | 22 |
| 5 | Brighton & Hove AlbionBrighton | 12 | 6 | 4 | 2 | 21 | 16 | 5 | 22 |
| 6 | Tottenham HotspurSpurs | 12 | 6 | 1 | 5 | 27 | 13 | 14 | 19 |
| 7 | Nottingham ForestNott'm Forest | 12 | 5 | 4 | 3 | 15 | 13 | 2 | 19 |
| 8 | Aston Villa | 12 | 5 | 4 | 3 | 19 | 19 | 0 | 19 |
| 9 | Fulham | 12 | 5 | 3 | 4 | 17 | 17 | 0 | 18 |
| 10 | Newcastle UnitedNewcastle | 12 | 5 | 3 | 4 | 13 | 13 | 0 | 18 |
| 11 | Brentford | 12 | 5 | 2 | 5 | 22 | 22 | 0 | 17 |
| 12 | Manchester UnitedMan Utd | 12 | 4 | 4 | 4 | 13 | 13 | 0 | 16 |
| 13 | Bournemouth | 12 | 4 | 3 | 5 | 16 | 17 | -1 | 15 |
| 14 | West Ham UnitedWest Ham | 12 | 4 | 3 | 5 | 15 | 19 | -4 | 15 |
| 15 | Everton | 12 | 2 | 5 | 5 | 10 | 17 | -7 | 11 |
| 16 | Leicester CityLeicester | 12 | 2 | 4 | 6 | 15 | 23 | -8 | 10 |
| 17 | Wolverhampton WanderersWolves | 12 | 2 | 3 | 7 | 20 | 28 | -8 | 9 |
| 18 | Ipswich TownIpswich | 12 | 1 | 6 | 5 | 13 | 23 | -10 | 9 |
| 19 | Crystal Palace | 12 | 1 | 5 | 6 | 10 | 17 | -7 | 8 |
| 20 | Southampton | 12 | 1 | 1 | 10 | 9 | 24 | -15 | 4 |
| > Premier League Full Table | |||||||||
