While still working as a community rugby officer for Munster Rugby, Brace attended a schools tournament and was asked to referee a match because they were short of an official. The match was between Abbey CBS and St Mary's Town School. He was encouraged to take up refereeing by John Lacey. Brace subsequently took charge of matches in both the British and Irish Cup and All-Ireland League. On 3 April 2015 he refereed the 2014–15 British and Irish Cup final between Worcester Warriors and Doncaster Knights. On 7 May 2016 he refereed the 2015–16 All-Ireland League final between Clontarf and Cork Constitution. On 6 September 2015 Brace made his Pro14 debut when he took charge of a 2015–16 match between Cardiff Blues and Zebre.