Morillo made 6 appearances for the rookie-level Arizona League Dodgers in 2018. He returned to the affiliate for the 2019 campaign, also making 3 starts for the Ogden Raptors, and posted a cumulative 2-2 record and 2.93 ERA with 75 strikeouts across 58+1⁄3 innings pitched.[2] Morillo did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[3]
Morillo made one scoreless outing for the High-A Great Lakes Loons in 2021, but missed the remainder of the year and all of the 2022 campaign due to injury. He returned to action in 2023 with the Single-A Rancho Cucamonga Quakes and Great Lakes. In 35 appearances split between the two affiliates, Morillo compiled an 0-2 record and 4.86 ERA with 48 strikeouts and four saves across 33+1⁄3 innings pitched.[4]
Morillo spent the 2024 campaign with the Double-A Tulsa Drillers, registering a 5-2 record and 4.76 ERA with 50 strikeouts across 41 appearances out of the bullpen.[5] He elected free agency following the season on November 4, 2024.[6]
Arizona Diamondbacks
On November 14, 2024, Morillo signed a minor league contract with the Arizona Diamondbacks.[7] He was assigned to the Triple-A Reno Aces to begin the 2025 season.
On April 19, 2025, the Diamondbacks promoted Morillo to the major leagues.[8][9] Morillo made his debut later that day against the Chicago Cubs, pitching one scoreless inning and striking out two batters.[10]