Colchester guaranteed another season in League One as goals from Gavin Massey and Tom Eastman saw off Carlisle.
The Essex club needed a win to guarantee their survival in the third tier and their nerves were finally settled when Massey struck.
Massey reacted quickest to head into the net after Billy Clifford's effort rebounded off the crossbar.
Eastman wrapped up the three points as he headed in David Wright's looping ball from the by-line.
VIEWS FROM THE DRESSING ROOM
Colchester United manager Joe Dunne told BBC Essex:
"Mission accomplished. We talked about getting the job done ourselves, and I thought we were magnificent.
"We had a gameplan that worked spot-on. We frustrated Carlisle, killed the game a bit, made sure we were counter-attacking.
"I thought we controlled the first half and the game developed into exactly what we wanted it to. It doesn't matter what the other team did - we've done it."
Carlisle United 20 Gillespie 03 Robson 05 Livesey 22 Mustoe Booked 23 O'Hanlon 08 Noble Booked 12 Thirlwell Booked (Manset - 52' ) 16 Potts 21 Berrett 09 Loy (Salmon - 67' ) 14 Miller Substitutes 01 Collin 02 Simek 06 Murphy 18 Todd 27 Salmon 10 Manset 17 Beck Colchester 44 Walker 02 Wright 04 Okuonghae 18 Eastman 20 Wilson 25 White 41 Clifford (O'Toole - 82' ) 15 Bean (Izzet - 87' ) 39 Porter (Garmston - 70' ) 17 Ibehre 21 Massey Substitutes 01 Cousins 03 Garmston 08 O'Toole 10 Izzet 14 Bond 11 Sears 22 Smith