The 21-year-old, who is yet to make a first-team appearance for the Stamford Bridge club, spent the first half of the campaign on loan at Bristol Rovers, where he featured 14 times.
Walker joins fellow Chelsea youngsters Archange Nkumu and Billy Clifford at the Colchester Community Stadium.
Only Hartlepool, Scunthorpe and Carlisle have conceded more goals than Colchester in League One this season.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Arsenal | 34 | 24 | 5 | 5 | 82 | 26 | 56 | 77 |
| 2 | Manchester CityMan City | 33 | 23 | 7 | 3 | 80 | 32 | 48 | 76 |
| 3 | Liverpool | 34 | 22 | 8 | 4 | 75 | 34 | 41 | 74 |
| 4 | Aston Villa | 34 | 20 | 6 | 8 | 71 | 50 | 21 | 66 |
| 5 | Tottenham HotspurSpurs | 32 | 18 | 6 | 8 | 65 | 49 | 16 | 60 |
| 6 | Manchester UnitedMan Utd | 33 | 16 | 5 | 12 | 51 | 50 | 1 | 53 |
| 7 | Newcastle UnitedNewcastle | 33 | 15 | 5 | 13 | 69 | 54 | 15 | 50 |
| 8 | West Ham UnitedWest Ham | 34 | 13 | 9 | 12 | 54 | 63 | -9 | 48 |
| 9 | Chelsea | 32 | 13 | 8 | 11 | 61 | 57 | 4 | 47 |
| 10 | Bournemouth | 34 | 12 | 9 | 13 | 49 | 60 | -11 | 45 |
| 11 | Brighton & Hove AlbionBrighton | 33 | 11 | 11 | 11 | 52 | 54 | -2 | 44 |
| 12 | Wolverhampton WanderersWolves | 34 | 12 | 7 | 15 | 46 | 54 | -8 | 43 |
| 13 | Fulham | 34 | 12 | 6 | 16 | 50 | 54 | -4 | 42 |
| 14 | Crystal Palace | 34 | 10 | 9 | 15 | 44 | 56 | -12 | 39 |
| 15 | Brentford | 34 | 9 | 8 | 17 | 52 | 59 | -7 | 35 |
| 16 | Everton | 34 | 11 | 8 | 15 | 36 | 48 | -12 | 33 |
| 17 | Nottingham ForestNott'm Forest | 34 | 7 | 9 | 18 | 42 | 60 | -18 | 26 |
| 18 | Luton TownLuton | 34 | 6 | 7 | 21 | 47 | 75 | -28 | 25 |
| 19 | Burnley | 34 | 5 | 8 | 21 | 37 | 69 | -32 | 23 |
| 20 | Sheffield UnitedSheff Utd | 34 | 3 | 7 | 24 | 33 | 92 | -59 | 16 |
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