[1][3][4][5][7] He stayed at Poli for a decade, going through all the stages of the youth center, playing right midfielder and even catching a match for the senior team in a friendly with Flamura Roșie Arad in 1954, where his direct opponent was József Pecsovszky.
[4] From 1971 until 1972 he was the assistant coach of Nicolae Dumitrescu at UTA Arad, the team reaching the quarter-finals of the 1971–72 UEFA Cup and finishing the championship on the second place.
[4][5][9][10] In 1972 at age 36 he returned at Politehnica in Divizia B, helping the team finish on the first place in his first season, earning promotion to the first league after a absence of five years.
[1][3][4][7][11] He was the assistant coach of Constantin Cernăianu at Romania's students football team, winning the Universiade gold medal in the 1974 edition that was held in France.
[1][5][12][13] In 1975 he went to coach Jiul after the 22nd round of the season, helping the team avoid relegation, managing to earn a 2–0 win over Dinamo București.
[14] After a period spent at CFR Timișoara, Ionescu went to coach UTA Arad where he was dismissed by the end of his second season, leaving them on the 12th place from 18 teams, the club relegating without him.
[1][4] After one year spent at Aurul Brad, in 1984 Ionescu signed with Corvinul Hunedoara where in the 1985–86 season the team impressed by having a three goals per home game scored, including a 9–0 win over Rapid București.
[1][3][4][7][17] Shortly afterwards he signed with Sportul Studențesc București where he worked with Lucescu's son, Răzvan who was a player but had no problem with him.
[1][3][4][7][17] In 1990 he returned for a second spell at Corvinul but left after the clubs officials allegedly asked him to throw a game with Universitatea Craiova.
[1][3][4][18] He then participated with the club at the 1992–93 UEFA Cup edition where in the first round they faced Real Madrid, obtaining a 1–1 at Timișoara and losing with 4–0 on Santiago Bernabéu.
[4][8] Ion Ionescu has a total of 496 matches as a manager in the Romanian top-division, Divizia A consisting of 194 victories, 89 draws and 213 losses.