The new head coach has overseen six wins, two draws and four defeats in his first 12 games in the Blues hot seat.
The 36-year-old was the man chosen to succeed Danny Cowley in the dugout at PO4 and quickly turned Pompey’s fortunes - taking maximum points in his opening two games.
But how does Mousinho's win record compare to his predecessors?
We’ve compared the current head coach’s win percentage to see how his figures rank to every Blues boss since 2000.
Not just that, but we’ve taken a look at their overall record during their time at PO4 to see whether it is too early to judge the former Oxford defender's Fratton tenure.
Here’s how the numbers compare.
. John Mousinho
John Mousinho has won half of his games in charge of Pompey. Photo: Graham Hunt
. Guy Whittingham - 0 per cent
Record in first 12 games: W0 D3 L9; Overall win percentage: 21.6 per cent. Photo: Allan Hutchings
. Graham Rix - 16.6 per cent
Record in first 12 games: W2 D5 L5; Overall win percentage: 28.6 per cent. Photo: MARK THOMPSON
. Tony Adams - 25 per cent
Record in first 12 games: W3 D5 L4; Overall win percentage: 18.2 per cent. Photo: Robin Jones
. Alain Perrin - 25 per cent
Record in first 12 games: W3 D3 L6; Overall win percentage: 19.1 per cent. Photo: Richard Heathcote
. Richie Barker - 25 per cent.
Record in first 12 games: W3 D5 L4; Overall win percentage: 20 per cent. Photo: Joe Pepler
1. John Mousinho
John Mousinho has won half of his games in charge of Pompey. Photo: Graham Hunt
2. Guy Whittingham - 0 per cent
Record in first 12 games: W0 D3 L9; Overall win percentage: 21.6 per cent. Photo: Allan Hutchings
3. Graham Rix - 16.6 per cent
Record in first 12 games: W2 D5 L5; Overall win percentage: 28.6 per cent. Photo: MARK THOMPSON
4. Tony Adams - 25 per cent
Record in first 12 games: W3 D5 L4; Overall win percentage: 18.2 per cent. Photo: Robin Jones