We use the preposition “in” with the adjective “interested”. We don’t usually use “interested on” in English.
I am interested in the job.
I am interested on the job
We use the preposition “in” when we want to show that something exists in a volume. That could be “in a park”, “in a field” or “in a bottle” or it could be something within some metaphorical boundary like “in a debate”. Let’s look at some examples of ”interested” with the preposition “in”:
It was great, everybody was interested in the debate.
You need to be more interested in class.
We don’t usually use “on” with “interested”. There might be certain instances where you can use “interested on” when we need to use “on” with the noun that follows “interested”.
He seemed really interested on the radio.
Notice that the meaning above does not convey what you are “interested in”.
We can also use “interested to” but “to” is not a preposition in this case but an infinitive. We use “interested to” with verbs of perception like “see” and “hear”.
I’d be interested to see how this turns out.
I’d be interested to hear about how it went.
We use the preposition ”in” with the adjective “interested”. We can also use “to” after “interested” but this is when we want a verb to follow “interested”.