Pompey confirmed the sale of the club to businessmen Balram Chainrai, Levi Kushnir and Deepak Chainrai last week and the players rewarded their new owners with all three points.
Strikes in either half from Sonko and Lawrence helped them to a fourth successive win as Portsmouth moved above Billy Davies' men and into 10th in the Championship.
Forest had only themselves to blame after they failed to take the initiative when Paul Anderson had cancelled out Sonko's opener.
Pompey and Forest came into the fixture on the back of victories over Hull and Ipswich respectively and as such, neither manager felt the need to change their starting line-ups.
However, Portsmouth manager Steve Cotterill was able to field seven substitutes for the first time this season.
It was Forest who had the first chance of the match though as in-form striker Lewis McGugan spurned a glorious chance to add to his goal haul.
The striker, who has scored seven in this campaign, was put through on goal by Radoslaw Majewski and although Jamie Ashdown parried McGugan's first effort, the Forest star was then wide with the goal at his mercy.
At the other end, Hayden Mullins beat the offside trap but he fired over when one-on-one with Forest keeper Lee Camp.
His miss did not prove particularly crucial as Sonko broke the deadlock in the 18th minute.
The defender rose highest from Lawrence's inch-perfect corner and powered home a header to register his first goal for the south coast club.
The omens did not look good for Forest as they had lost five successive games to Portsmouth, however, Anderson levelled matters with a stunning header nine minutes later.
McGugan's right-wing cross found Anderson in the area and the midfielder had to be at full stretch to head past Ashdown.
On the balance of play, it was no more than the Reds deserved and though they continued to assert pressure, they failed to force Ashdown into action for the remainder of the half.
Pompey came firing out of the traps in the second half and David Nugent, who had cut a forlorn figure in the first-half, was particularly threatening.
The former Preston man's 25-yard strike narrowly went over the bar and he went closer with a chip on the edge of the area that Camp did well to tip over the bar.
Portsmouth continued to launch wave after wave of attack and it came as no surprise when Liam Lawrence gave the hosts the lead in the 62nd minute.
Utaka's ball into the box fell to Lawrence and he drilled the ball through a sea of bodies and into the net.
The midfielder's strike may have taken a deflection which wrongfooted Camp although if the Forest keeper was at any fault for the goal, he made up for it when he saved well from Utaka's 12-yard strike.
Luke Chambers should have done better late on as his unmarked header from six yards sailed wide as Forest lost for just the third time in the league this season.