Say Impulse response of an LTI is Aperiodic and I pass a Periodic signal, now I need to find the Fourier Series representation of the output.

Since Convolution in time domain if multiplication in Frequency Domain, I think that converting both signals in their respective Frequency Domain and Multiplying them. Therefore finding the Fourier Series of first and Transform for second. Is it a correct way?

Any help is highly appreciated.