Some waited for around an hour and a half in the queue which stretched all the way back passed the entrance to Northampton Town FC's stadium.
Organiser John Scarrott said they did not expect so many visitors but was pleased to be able to give them some entertainment in a Covid-safe environment.
"There were a lot of happy smiling faces and that's what we like to see - the motto on the side of our trucks is: 'Our business is fun,' and it looks like we achieved that."
All the usual rides and attractions are in the north car park on Walter Tull Way every day until Sunday, May 9 - entry is free but each ride costs £1.50 per person.
To thank NHS workers for their efforts during the pandemic, the funfair will be free for them from 3-5pm on Wednesday, April 28.
There are a long list of measures to ensure visitors stay safe such as limited capacity on rides, enhanced cleaning and Track and Trace for everyone aged over 16.
Visitors must stick to the 'rule of six', cash and contactless payments are accepted, social distancing must be adhered to and hand sanitisers are available around the site.
Face masks are not mandatory as it is all outdoors but masks are available to buy upon arrival should anyone feel the need to wear one.
The funfair is open from 5-10pm on weekdays and 2-10pm at the weekend.
Flick through our photos from Saturday (April 17) - can you spot yourself or anyone you know? All pictures by Kirsty Edmonds.