[1][2][3] Afterwards he went to play for Sporting Club Pitești, Vulturii Textila Lugoj and Sportul Muncitoresc Găvana before arriving at Juventus București where he made his Divizia A debut on 6 April 1947, being used by coach Emerich Vogl in a 4–1 victory against Libertatea Oradea.

[1][2][3] Ionescu played five games at international level for Romania, making his debut on 20 June 1948 under coach Iuliu Baratky in a 3–2 home victory against Bulgaria at the 1948 Balkan Cup.

[2][3][10][11] He went to coach the senior squad of Dinamo București where he showed his availability of discovering and promoting young players like Ion Pârcălab whom after transferring him from UTA Arad turned into one of the best forwards in Europe, Mircea Lucescu whom he saw playing football on a field covered with gravel, Cornel Dinu whom he noticed while playing for Metalul Târgoviște in the quarter-finals of the 1964–65 Cupa României against Dinamo, 16 year-old Florea Dumitrache whom he saw only 10 minutes playing junior level football at TUG București after which he decided to transfer him, Constantin Frățilă, Ilie Datcu, Gabriel Sandu, Florin Cheran and Alexandru Sătmăreanu, all of them together with other players he coached at Dinamo like Ion Nunweiller, Lică Nunweiller and Gheorghe Ene were important players for Romania's national team in the 1960s and 1970s.

[2][3][7][15] He had his first coaching experience outside Romania in Turkey at Fenerbahçe with whom he won the Turkish First Football League 1969–70 and a TSYD Cup together with his former Dinamo players, Ion Nunweiller and Ilie Datcu.

[2][3][16] Traian Ionescu also worked at Sportul Studențesc București, Olimpia Satu Mare, Jiul Petroșani with whom he reached the 1977–78 Balkans Cup final, SC Bacău, Petrolul Ploiești, Steaua București, Chimia Râmnicu Vâlcea, Olt Scornicești, CSM Reșița, having a total of 287 matches as manager in Divizia A, consisting of 128 victories, 70 draws and 89 losses, also having a second coaching experience outside Romania at Morocco's Olympic team.