The Portaferry woman clocked 4:01.46 as she ran superbly to finish ninth in a thrilling race won by Britain's Laura Muir at the Diamond League meeting.
Mageean, 24, passed several athletes on the final lap as Muir ran sensationally to improve her own British record.
The Scottish athlete ran the fastest time of 2016 as she won in 3:55.22.
Mageean's time, which improved her own Northern Ireland record, moved her to second on the all-time Irish list behind Sonia O'Sullivan's national mark of 3:58.85 set in Monaco in 1995.
The county Down woman failed to qualify from the Olympic semi-finals in Brazil some five weeks after winning a bronze medal at the European Championships.
Muir only managed to finish seventh in Rio but produced a magnificent front-running display in Paris to beat a field which was probably stronger than the Olympic final.
After being among the leaders early on, Mageean dropped back to near the tail of the field over the second and third laps before producing a strong late run to move up the field.
The Northern Irishwoman achieved her previous personal best of 4:06.49 in Italy last September but her lack of races in major Grand Prix meetings led to the belief that she was capable of running much faster and so it proved.
The pacemaker in Saturday's race took the field through in a brisk 63.97 seconds over the first lap which set up the real possibility of a fast race.
Muir finished 1.50 seconds ahead of Kenya's Olympic champion Faith Chepngetich Kipyegon with Rio fifth placer, Dutchwoman Sifan Hassan (3:57.13) in third.
American Shannon Rowbury matched her Rio fourth place as she clocked 3:58.00 while Ethiopia's Dawit Seyaum (3:58.09), Olympic bronze medallist Jenny Simpson (3:58.19), Ethiopian Besu Sado (3:59.96) and Poland's Sofia Ennaoui (4:01.00) were also ahead of Mageean.
Ciara Mageean regrouped from her Olympic Games disappointment as she cut over five seconds off her 1500m personal best in Paris.