I have deployed my kubernetes application on AKS, it uses the Internal Loadbalancer without a separate Ingress Controller.
Currently the service is accessible using http protocol and I want to secure the service. How do I enable https and where should I install the certificate?
The internal loadbalancer is a layer 4 service, you will need a layer 7 ingress controller like Azure Application Gateway Ingress Controller or roll your own ingress controller for SSL.
see: Configuring an AKS load balancer for HTTPS access