The 28-year-old Wimbledon champion has only lost twice this year but found herself a break down in both sets before she recovered to seal her first victory since winning the Prague Open a month ago.
World number two Halep, who had skipped the U.S. Open due to COVID-19 concerns and opted to stay in Europe and practice on the claycourts ahead of the French Open, looked sluggish at the Foro Italico with 14 winners offset by 15 unforced errors.
“I was a little bit tight at the beginning, it was tough to get a rhythm in the whole match,” Halep told reporters.
“It’s always tough in the first match of the tournament and she played really well. I felt like I played very well when needed.”
Halep had received a bye into the second round but was far from her best on serve and was broken five times in the match.
However, Paolini was also let down by seven double faults in the match and Halep capitalised on her second serve, winning 15 of 17 points to take the opening set.
She switched gears late in the second to take the game away from the Italian, who was playing a top-10 player for only the second time in her career, as Halep finished the match after converting her eighth break point.
Second seed Karolina Pliskova started her title defence with a 6-3 6-3 win over Barbora Strycova, converting four break points and smashing 26 winners past her Czech compatriot.
Meanwhile, Belarusian Victoria Azarenka beat American Venus Williams 7-6(7) 6-2 to set up a second-round clash with third seed Sofia Kenin.
After winning the Western & Southern Open last month and losing the U.S. Open final in New York over the weekend, Azarenka had no problems switching from hardcourt to clay in just four days.
“Different surface was definitely challenging but I feel like I adapted very well,” Azarenka said. “I felt that this was a great match for me to figure it out, the first match on clay. Reporting by Rohith Nair in Bengaluru and Manasi Pathak in Chennai, editing by Pritha Sarkar, Christian Radnedge and Toby Davis