In August 2018 it was reported, that S.D. Aucas had bought 50% of Vallecilla's rights for $80,000, and that he would join the club permanently from the 2019 season, with Cuenca still holding a sell-on percentage.[5][6][better source needed]
Joining Aucas for the 2019 season, Vallecilla appeared in five total matches, including an appearance in the quarterfinals of the Serie A playoffs.[7]
For the 2020 season, Vallecilla was loaned out to Barcelona SC with an option to buy.[8][9] He made 14 league appearances for Barcelona, and also appeared in the 2020 Copa Libertadores. After the season, the club decided not to trigger the option to make his stay permanent.
Vallecilla then returned to Aucas for the 2021 season.[10]
FC Cincinnati
On 5 April 2021, Vallecilla joined Major League Soccer club FC Cincinnati on loan for the 2021 season with an option to buy.[11][12] He made his debut for the side on 16 May 2021 in their 3–2 home defeat against Inter Miami. The following match, Vallecilla scored his first goal for Cincinnati in their 2–1 victory over CF Montréal, scoring the equalizer in the 86th minute.[13] His second goal for Cincinnati came against the same opposition on 17 July in their 5–4 defeat at Saputo Stadium.[14]
On 1 December 2021 Cincinnati confirmed, that they had triggered the buying option in Vallecilla's contract, adding him to the squad for the 2022 season.[15][16]
Colorado Rapids
On 28 March 2022, Colorado Rapids announced that they acquired Vallecilla for $800,000 in General Allocation Money with extra performance-based fees.[17]
Loan to Columbus
On 3 March 2023, Vallecilla was loaned to the Columbus Crew for $175,000 in General Allocation Money, with the Crew having a purchase option as well.[18]
Universidad Católica
At the end of December 2023 it was confirmed, that Vallecilla would return to Ecuador, having signed with Universidad Católica.[19] He left Catolica at the end of the year after 40 games for the club in all competitions.[20]
