Arcángel told Billboard Español that he had plans release an EP on November 2021, but would eventually be scrapped after hearing about the death of his brother, Justin Santos, who died in a car accident at the Teodoro Moscoso Bridge.[1] A year after his death, Arcángel and his mother, Carmen Rosas, visited the bridge and designated it a new name, the Justin Santos Bridge.[2] He released "JS4E" as a tribute, on November 21, 2022, along with its accompanying music video.[3] He announced Sr. Santos in late November 2022, with the addition of the single "La Jumpa" with fellow collaborator Bad Bunny; the former was stated to be dedicated to his brother.[4][5][6]
In the United States, Sr. Santos debuted at number 37 on the Billboard 200 with 19,000 album-equivalent units. In addition, it also debuted at number three on the Top Latin Albums and number two on the Latin Rhythm Albums chart.[7] It was also named as one of the best Latin music albums of 2022 by Billboard.[8] He also embarked the Just in Time Tour to support the album, which began on August 26, 2023, in Chicago, and ended on October 1, 2023, in Orlando, Florida.[9]