A first-half Westly strike earned Dundee a huge three points as they look to steady the ship and avoid the drop and remain in the top-flight.
Dhanda had the first real big chance after ten minutes as he fired a tame effort from the edge of the box which was easily gathered by Ross Sinclair in goals.
Dundee shortly fired ahead after a slack pass at the back allowed Dundee to attack with Congreve twisting-and-turning on the right flank, he then whipped a ball into the box where Joe Westley struck it home to steer Pressley’s men away from the relegation fight.
The hosts nearly had a second as Dhanda struck the ball goal bound but was deflected onto the bar by a St Mirren body to deny Dundee a second.
Congreve again whipped a low ball in, it found Westley once again but his effort went just wide of the target.
St Mirren were denied a penalty just before the break after a pretty dreadful half by the Buddies’ but after a lengthy VAR check, the penalty was denied.
Into the second half, Richardson took on a shot from distance which ended up being palmed away by the Dundee number one to deny an equaliser for the Paisley outfit.
St Mirren had another big chance which saw Campbell deliver a ball into the box and Mandron met with it but his strike fired just wide.
Not much drama in the second period going into the 70 minute mark as St Mirren struggle to pull one back despite a slightly better half than their first half showing.
St Mirren again came close as Idowu made a darting run towards goal and took on a strike from a very tight angle which rattled the side netting as St Mirren keep pushing for an equaliser.
Congreve had a chance to see off the game with a right-footed strike inside the box but too many touches allowed St Mirren bodies to come back and block his effort.
Dundee had a massive late chance with a ball across goal mouth but the Dundee forward unable to tap the ball into the net to go two clear.
Dundee see out a vital win at Dens as they continue their relegation fight as their Premiership status for next season looks very likely and for the visitors, well they drop into 11th as they go into the fight with Kilmarnock – which they will meet next Saturday in Paisley.
Dundee: McCracken (6), Astley (7), Wright (7), Murray (6), Halliday (7), Yogane (8), Westley (8), Congreve (7), Dhanda (9), Hamilton (7), Graham (7).
Substitutes: O’Hara (7), Robertson (7), Hay (6), Samuels (6), Koumetio (6).
St Mirren: Sinclair (6), Richardson (6), Tanser (5), King (6), O’Hara (6), Idowu (6), Devaney (6), Mandron (5), Campbell (6), Freckleton (6), Phillips (5).
Substitutes: McMenemin (6), Fraser (6), Young (6).
