Finishing in first place in the (1b ind) Freestyle, Pearson has only been riding his horse, Gentleman, since January.
'I was more nervous for these three competitions than I have ever been for any competition in my life,' said Pearson.
'I rode my heart out and I don’t think Gentleman will ever know how much he has changed my life.'
Pearson and Gentleman topped the table with a stunning score of 77.06%, winning Pearson a third gold in as many Games.
In second place was Pearson's Paralympics GB teammate, 22 year old Ricky Balshaw on Deacons Giorgi.
The ParalympisGB Equestrian squad have won a total of 10 medals in 2008, more than in any other Paralympic Games.
Read the latest from ParalympicsGB.