When someone greets you by saying ‘Mucho Gusto’ (which translates to ‘Nice to meet you’ in English), the most common and appropriate response is ‘Igualmente,’ meaning ‘Likewise.’ This reply shows that you reciprocate the sentiment and appreciate the meeting.
Alternatively, you can also say ‘El gusto es mío’ (The pleasure is mine) if you want to express your own pleasure in the introduction. It’s a warm and friendly way to acknowledge the greeting. Both responses are polite and will be well-received.