On 23 June 2012, Alonso won his 100th cap for Spain in the quarter-final of Euro 2012 against France; he celebrated the occasion by scoring both of Spain's goals to send them into the semi-finals.
Pada tanggal 23 Juli 2012, Alonso mengumpulkan caps ke-100 bagi Spanyol di perempat final Euro 2012 saat melawan Prancis: ia merayakan kesempatan itu dengan mencetak dua gol bagi Spanyol dan membawa mereka melaju ke semi-final.