The 23-year-old has agreed a one-year deal at Spotland, subject to Football League clearance.
Mendez-Laing left Peterborough earlier this summer after spending the last three months of last season on loan at Cambridge United.
Rochdale have now brought in four new players ahead of next Tuesday's transfer deadline, with Lewis Alessandra, Donal McDermott and Jim McNulty also being recruited.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | York City | 17 | 11 | 5 | 1 | 33 | 12 | 21 | 38 |
| 2 | Forest Green RoversForest Green | 17 | 11 | 4 | 2 | 33 | 14 | 19 | 37 |
| 3 | Barnet | 17 | 11 | 1 | 5 | 34 | 20 | 14 | 34 |
| 4 | Gateshead | 17 | 10 | 3 | 4 | 28 | 22 | 6 | 33 |
| 5 | Oldham AthleticOldham | 17 | 8 | 7 | 2 | 25 | 17 | 8 | 31 |
| 6 | Rochdale | 17 | 9 | 3 | 5 | 27 | 16 | 11 | 30 |
| 7 | Yeovil TownYeovil | 17 | 8 | 4 | 5 | 21 | 15 | 6 | 28 |
| 8 | Halifax TownHalifax | 17 | 7 | 5 | 5 | 19 | 16 | 3 | 26 |
| 9 | Solihull MoorsSolihull | 17 | 7 | 4 | 6 | 26 | 28 | -2 | 25 |
| 10 | AltrinchamAltrincham | 17 | 6 | 6 | 5 | 26 | 23 | 3 | 24 |
| 11 | Eastleigh | 17 | 6 | 5 | 6 | 25 | 25 | 0 | 23 |
| 12 | Dagenham & RedbridgeDag & Red | 17 | 5 | 7 | 5 | 27 | 18 | 9 | 22 |
| 13 | Sutton UnitedSutton | 17 | 6 | 4 | 7 | 25 | 26 | -1 | 22 |
| 14 | Tamworth | 17 | 6 | 4 | 7 | 20 | 28 | -8 | 22 |
| 15 | Southend UnitedSouthend | 17 | 5 | 6 | 6 | 20 | 20 | 0 | 21 |
| 16 | Hartlepool UnitedHartlepool | 17 | 5 | 6 | 6 | 18 | 21 | -3 | 21 |
| 17 | Aldershot TownAldershot | 17 | 4 | 6 | 7 | 21 | 27 | -6 | 18 |
| 18 | Fylde | 17 | 5 | 3 | 9 | 23 | 36 | -13 | 18 |
| 19 | Woking | 17 | 4 | 5 | 8 | 18 | 24 | -6 | 17 |
| 20 | Braintree TownBraintree | 17 | 4 | 4 | 9 | 13 | 20 | -7 | 16 |
| 21 | Maidenhead UnitedMaidenhead | 17 | 4 | 4 | 9 | 21 | 30 | -9 | 16 |
| 22 | WealdstoneWealdstone | 17 | 3 | 6 | 8 | 16 | 25 | -9 | 15 |
| 23 | Boston UnitedBoston | 17 | 2 | 5 | 10 | 16 | 30 | -14 | 11 |
| 24 | Ebbsfleet | 17 | 1 | 5 | 11 | 15 | 37 | -22 | 8 |
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