The Italian club announced the arrival of the 21-year-old Spaniard on Thursday, although no financial details were revealed. Reports in Italy and Britain claim Fiorentina can sign Jimenez permanently for around 20 million euros at the end of the loan.
In a club statement, Fiorentina said: "ACF Fiorentina announces that it has acquired, on a loan basis with an option to buy, the sporting rights of player Alejandro Jimenez Sanchez from AFC Bournemouth."
Jimenez made 32 appearances in all competitions for Bournemouth last season, including 31 in the Premier League, and scored one goal after joining the club permanently from AC Milan in February following an initial loan spell.
However, the defender's campaign ended in difficult circumstances. Bournemouth left him out of the first-team squad in May while investigating social media posts linked to the player. The Premier League club did not provide further details, and Jimenez did not comment publicly at the time.
A graduate of Real Madrid's academy, Jimenez moved to AC Milan in 2023 before joining Bournemouth.