The Fiorentina left-back moved to the Stadium of Light on loan in January and has swiftly established himself as first choice under Gus Poyet with a number of assured displays.
Having played a crucial role in Sunderland's League Cup semi-final win over Manchester United - the first leg was his Sunderland debut - and featuring in last weekend's final defeat to Manchester City as well as the club's push for Premier League survival, Alonso is enthused by his time in the north east.
Despite that, he revealed he will go back to Italy at the end of the season, although he refused to rule out a return to Sunderland for next term.
"I'm very happy here at the moment, with the manager, the rest of the team, the staff, everything," said Alonso.
"I'm playing, that's the main thing. But I have two more years in Italy, so I will have to go back at the end of the season.
"I will have to do that. What happens in the summer, I don't know. I'm not thinking about that yet.
"I'm just enjoying my time here."