Davies played his club rugby for Llanelli and enjoyed a distinguished 46 cap career for Wales between 1985 and 1995. It was during this period that Welsh packs became far less dominant than in the glory days of the 1970s and Davies, along with David Pickering and Bob Norster, was one of the few class forwards that his side could muster.

The mustachioed Davies was a useful addition to the side mostly because of his offensive ability and the fact that he could play either as flanker, number eight or lock forward.

His career is also memorable for his involvement in the so-called "Battle of Cardiff" in 1987, an extremely violent clash between Wales and England that saw Davies wind up on the wrong end of lock Wade Dooley's fist. Davies' first international appearance came in a 24–15 victory over England in Cardiff, a game that saw his brother-in-law, Jonathan Davies, also make his debut. England, who had not won in Cardiff since 1963, led the game 15–12, before fullback Chris Martin failed to take a high kick and Davies (Jonathan) scored a crucial try. Davies' next appearance came in a 40–3 victory against Fiji at the Arms Park, and he marked the occasion by scoring two of his side's seven tries.

Following his playing career, Davies went to coach at Leeds for 10 years, helping them to take them from a national 3 team to a premiership club, with a Powergen Cup win as well. He returned to Wales as Director of Rugby for the Scarlets. Stints in the international arena followed with Davies branching out and coaching Namibia, taking them to several world cups and surpassing expectations.

His current role as Director of Rugby for World Rugby, a position he took over from Joe Schmidt, sees him travelling the world and helping to grow the game and the coaching of developing nations.