The Gialloblu were left to rue the officials' decision to disallow Andrea Coda's first-half goal but Roberto Donadoni's men were always second-best as they drifted towards a fifth defeat in six games.
Samp had been concerned with Icardi's lack of goals in recent weeks but the Argentinian ended his two-game drought by converting an easy finish following a poor mistake from Parma goalkeeper Antonio Mirante.
The victory propels Samp into 10th place, with a haul of 35 points giving Delio Rossi's men a healthy 14-point cushion above the relegation zone, but Parma can start looking over their shoulders having tumbled down to 13th.
It would be yet another poor outing for Mirante, who has now failed to keep a clean sheet for nine games, but he did make a fine stop from Eder in the opening exchanges.
Coda wheeled away to celebrate in the 17th minute after beating Sergio Romero at the other end but referee Paolo Valeri ruled his goal out for offside on the advice of his assistant.
Jonathan Biabiany's response left much to be desired as the Frenchman failed miserably with a lob before overcooking a pass to Marco Parolo, who had been unmarked inside the area.
With half-time fast approaching, Mirante kept Eder at bay once again and Parma took heart from their first-half display.
But the lack of cohesion that was evident in last week's defeat to Catania spread through the Gialloblu ranks again as play resumed, and Icardi took full advantage.
When Mirante made the wrong decision to rush out to collect a Marcelo Estigarribia free-kick in the 58th minute, Samp's prodigious Argentinian tapped his ninth goal of the season into an empty net.
Ten minutes later, Angelo Palombo almost allowed Parma an equaliser in calamitous fashion when clearing the ball off Amauri's feet and inches past his own goalmouth.
By now Parma were out of ideas and only some quick thinking from Jaime Valdes prevented Icardi poaching an easy second as the visitors chased shadows in the final stages.