Howie turned professional at the start of 2018 and played on the
Pro Golf Tour in his first year as a professional. He had a successful season, winning the Leipziger Golf Open in August, beating fellow-Scot
Chris Robb in a playoff. During the season he was also runner-up three times, third once and had three other top-10 finishes. In the event before his win, he had lost a playoff to
Ondřej Lieser in the Zell am See – Kaprun Open. He won the Order of Merit and gained a place on the
Challenge Tour for 2019. Howie was injured at the start of 2019 and had a poor season. He retained his place on the
Challenge Tour with a good performance at the
2019 European Tour Qualifying School in November. He had a better season in 2020 including a fifth-place finish in the
ISPS Handa UK Championship on the
European Tour, after a final round of 65. In May 2021 he won the
Range Servant Challenge on the Challenge Tour, finishing 7 strokes ahead of the runner-up,
Marcus Helligkilde. ==Amateur wins==