Can I choose a mix of Miles and cash to redeem my flight?

Yes. After choosing your flight and extras, select ‘Miles Plus Cash’ on the payment page, verify Cathay account, and select the number of miles you wish to use. The remaining cash amount will be displayed, which can be settled with your credit card.

More about redeeming HK Express flights

How do I pay for HK Express flights with my Asia Miles?
How many miles are required for HK Express flights?
Can I use Asia Miles to pay for HK Express promo fares?
Can I use Asia Miles to book a flight ticket for anyone other than myself?
Can I use Asia Miles to book a HK Express flight ticket for an infant or a child?
Can I use Asia Miles to pay for HK Express extras?
Why can’t I find the ‘Miles Plus Cash’ option on HK Express’ payment page?
Can I use Asia Miles to settle any tax and surcharge?
Can I rebook or refund my booking?
Can I earn Asia Miles for HK Express flight bookings?
I cannot successfully book a flight with Asia Miles on HK Express website. Who should I contact?