Neil and his guide and brother, Andrew, clocked a time of 1:08.91 to finish nearly half a second clear of the rest of the field to claim Great Britain's first gold medal in Beijing.
The 19-year-old said: "This is our first season doing Super-G. Initially when we came down and Andrew said we had gone in to first place, there was a bit of an anxious wait."
He added: "I wasn't thinking about it being a winning performance, I was just thinking that it was a good run. We put it all down on the line and really went for it and I'm just very happy with the performance - it felt good.
"There was a sketchy moment coming into the bowl but we knew we needed to get back on it and really went for it down the bowl, so I'm really happy with that."
Neil's guide and brother, Andrew, said the gold medal had surpassed their expectations.
"The race went as planned, at the race inspection we were like, this needs to be attacked from the get-go, and we went and did exactly that," Andrew said.
Simpson's historic success came hot on the heels of Menna Fitzpatrick winning silver for Team GB in the women's race, alongside her guide, Gary Smith, for the fifth Paralympic medal of her career.
The news means the 23-year-old becomes Great Britain's most successful ever Winter Paralympian and is more remarkable given that she recovered from a broken leg in March 2020, while her initial guide, Katie Guest, was ruled out of the Games because of a positive Covid test.
"To be here at all is a great achievement, but then to stand up on that podium is absolutely amazing," Fitzpatrick said. "I'm so proud of what we've achieved together.
"We went out to ski well and build on the day before and we are super, super happy."