Tom Lawrence scored twice in the second half after Bournemouth had responded to falling behind to Jason Knight's opener with goals from Jaidon Anthony and Dominic Solanke.
But although this was a first win in eight games for for a Derby side managed by former Manchester United and England striker Rooney, the three points they gained only took them to a total of zero points as they remained marooned at the foot of the Championship table.
Tuesday saw the Midlands club hit with a further nine-point penalty for breaches of English Football League accounting rules. That took the total points docked from the Rams this season to 21, after the club were previously deducted 12 points for entering administration.
That meant Derby kicked off against Bournemouth on minus three points and, despite erasing that deficit, relegation to the third tier of English football looks likely given Rooney's men are still 15 points shy of safety.
A further three-point penalty, which is suspended, will take effect if the club does not comply with the terms of a budget agreement for the rest of the 2021/22 season.
Standout matches today