Keady first came to prominence on the inter-county scene as a member of the Galway minor hurling team in the early 1980s. Due to the lack of any credible opposition in Connacht Galway were given an automatic pass into the All-Ireland semi-final. This happened at minor, under-21 and senior levels. In 1981 Keady lined out in his first minor championship decider. Unfortunately, it was Kilkenny who were victorious on that occasion. The following year he was a member of the Galway under-21 team. He came on as a substitute in the All-Ireland final against Cork; however, victory went to the Leesiders. In 1983 Galway reached the under-21 championship decider with Tipperary providing the opposition. The men from the West won the game by three points, giving Keady his first All-Ireland medal.
Keady subsequently joined the Galway senior panel. He first tasted major success in 1985 when Galway defeated reigning champions Cork in the All-Ireland semi-final, a victory which allowed Galway advance to the All-Ireland final. That game was a close affair; however, for the second year in-a-row Offaly got the better of Galway in the All-Ireland series. In 1986 Keady lined out in his second All-Ireland final. Cork were the opponents on that occasion but Galway were regarded as the red-hot favourites. The favourites tag counted for little as Cork won the exciting game on a score line of 4-13 to 2-15. In spite of losing another championship decider Keady was presented with a coveted All-Star award. In 1987 Keady captured a National Hurling League medal before his side reached the All-Ireland final once again. The experience gained in the two previous championship deciders showed against a Kilkenny side that was over the hill. Galway won the game on a score line of 1-12 to 0-9 and Keady collected his first senior All-Ireland medal. In 1988 Galway reached the All-Ireland final for the fourth consecutive year. Tipperary, the team Galway defeated in the previous year's semi-final, provided the opposition. In a close game Galway emerged victorious and Keady collected his second All-Ireland medal. Not only that but he was presented with the Man of the Match awards as well as a second All-Star award. Keady also finished the year by collecting the Texaco Hurler of the Year title.
While Keady was now regarded as the best hurler in the country, all of this was about to change in 1989. Shortly after collecting a second National League title Keady travelled to the United States to play an exhinition game for Laois against Tipperary. This was common practice at the time and the Galwayman was assured that he was eligible to do so. It later transpired that Keady had been wrongly informed and that he had played illegally. When he returned to Ireland the Games Administration Committee of the Gaelic Athletic Association decided to make an example of Keady and he was banned from playing for a year. This threw Galway's plans of capturing a third title in-a-row into disarray. The team even considered withdrawing from the championship, however, in the end they decided to play, albeit without the services of Keady. An ill-tempered All-Ireland semi-final saw Tipperary defeat Galway for the first time since 1971. In 1990 Galway reached their fifth All-Ireland final in six seasons. Just like in 1986 Cork provided the opposition and, once again, Galway were regarded as the red-hot favourites. Keady's side gave a brilliant first-half display and went seven-points up at one stage. In spite of this, Cork fought back to secure a victory on a score line of 5-15 to 2-21. It was one of the highest-scoring All-Ireland finals ever. Keady retired from hurling shortly afterwards.
Keady also lined out with Connacht in the Railway Cup inter-provincial competition. He captured two winners medal in this competition in 1986 as Connacht defeated Munster and again in 1991 after a defeat of the same team.