The Brit endured a difficult end to the previous season as he struggled to match the pace of teammate Nico Hulkenberg, but he has started this campaign in positive fashion.
"The performances of Paul confirm just how much he has matured as a driver. He's delivering consistently every week and we are reaping the rewards of all his hard work," Mallya told AutoSport.
"He suffered a difficult end to the 2012 season, but he's shown great mental strength and determination to regroup over the winter and recapture his best form. He's pushing the team on and demanding the best from everyone, which is what we need."
Di Resta narrowly missed out on his first podium finish at the Bahrain Grand Prix.