FC Kaiserslautern officially announced Jacob Rasmussen's permanent transfer to the club from RB Salzburg. The club did not disclose the length of Rasmussen's contract. FCK sporting director Marcel Klos stated that with Jacob, the club is signing a player whose qualities, including his heading ability and football intelligence, can further develop the club. Klos added that Rasmussen has a strong mentality and leadership qualities, both on and off the pitch, due to his international experience.

28-year-old Danish centre-back Jacob Rasmussen is leaving FC Red Bull Salzburg after half a year to join 2. Deutsche Bundesliga side 1. FC Kaiserslautern. Rasmussen had arrived in the summer as captain from Brøndby for a reported fee of 1.5 million euros but had recently been on the bench more frequently. The transfer was officially announced by Red Bull Salzburg. The club's Sporting Director, Marcus Mann, commented that although the player's stay was shorter than initially planned, Rasmussen had always behaved in an exemplary way and had given his full effort for the team. In the official press release, Rasmussen stated that he felt very comfortable at the club and in the city during his brief time there and is now looking forward to the exciting new challenge at Kaiserslautern. In the 2025/2026 season, he made 16 Bundesliga appearances for Salzburg, providing one assist. He has yet to be capped by Denmark. According to Transfermarkt, his current market value is €1.80m.