Jansen eventually earned a recall for several UEFA Euro 2008 qualifiers, including the 6–0 hammering of San Marino in which he scored his first international goal. Despite fears of injury he sustained against Serbia in a friendly match on 31 May 2008, Jansen was nevertheless a part of Joachim Löw's squad for the main tournament. Jansen played his first match of the tournament, playing the full 90 minutes in the 2–0 win against first group opponent Poland. He was then benched in Germany's 2–1 loss in the second group stage match against Croatia, but suffered a shoulder injury. Jansen returned as a substitute against Portugal in the quarter-finals in a 3–2 win and did so again against Turkey in the semi-finals, a 3–2 win. In the final, Jansen came on as a second-half substitute for Lahm, as he played and defended for the remainder of the match, which saw Germany lose 1–0 against Spain.