He previously played in Nippon Professional Baseball (NPB) for the Tohoku Rakuten Golden Eagles from 2014 to 2023.

[4] On October 11, 2023, Matsui had exercised his international free agent rights to be released from the Golden Eagles to seek a Major League Baseball contract.

[5] On December 23, 2023, Matsui signed a five-year contract worth $28 million guaranteed with the San Diego Padres of Major League Baseball.

[6][7] The contract included an opt out after both the third and fourth seasons and an injury clause which would change the fifth and final year of the contract into a $7 million club option in the case of Matsui suffering a "serious elbow injury" during the length of the deal.

[11] Matsui was selected at the 2019 WBSC Premier12[12] but on October 21, it was announced that he would not participate due to left elbow discomfort.