One day only park hopper

[atomicity]

Is it possible to purchase multi-day park passes but only have one day as a park-hopper?

 

[Weather_Lady]

No, I'm afraid not. It's an "all or nothing" add-on.

 

[Atlantix2000]

You could buy a multi-day ticket covering the whole trip and a single day park hopper but since single days are more expensive, it might not actually be cheaper. So for an example 5 day trip you could buy a 3 day ticket (which would be good for 3 days in a 5 day window and doesn't have to be used consecutively) and a 1 day park hopper ticket and use them like this (or any other combination):
Monday - Use Day 1 of 3-day ticket at MK
Tuesday - Use Day 2 of 3-day ticket at AK
Wednesday - Use park hopper 1-day ticket at MK and DHS
Thursday - Relax at your resort or shop at Disney Springs
Friday - Use Day 3 of 3-day ticket at Epcot