His departure was confirmed after the Southern Tigers sealed their seventh consecutive Malaysian Super League title with a 4-1 win over Sabah on Friday.
The 23-year-old Malaysia international scored twice in the match.
"JDT would like to wish Safawi Rasid all the best as he leaves for Portuguese Primeira Liga side Portimonense SC tonight.
"Safawi has been an excellent servant to the Southern Tigers since his debut on 27 January 2017. The 23-year-old has made 101 appearances for JDT, notching 47 goals and 18 assists.
"Safawi has won four Malaysia Super League titles, two Malaysia Cups and three Charity Cups with the Southern Tigers," posted the Johor side on social media.
Selamat Maju Jaya kepada Safawi. Saya berdoa semoga anda berjaya. Pintu kelab JDT sentiasa terbuka untuk Safawi. This is not the end, it's only the beginning.— JOHORSouthernTigers (@OfficialJohor) October 3, 2020
HRH Major General Tunku Ismail Ibni Sultan Ibrahim, Crown Prince of Johor pic.twitter.com/z9WSPx4D5B
Safawi's new club, who began the 2020 Primeira Liga campaign with one draw and one defeat, face Sporting on Monday morning (Malaysian time), live on Astro Supersport 2 (CH812 HD).