Matches were scheduled to be played at the stadium of the team named first on the date specified for each round, which was always a Saturday. Some matches, however, might be rescheduled for other days if there were clashes with games for other competitions or the weather was inclement. If scores were level after 90 minutes had been played, a replay would take place at the stadium of the second-named team later the same week. If the replayed match was drawn further replays would be held until a winner was determined. If scores were level after 90 minutes had been played in a replay, a 30-minute period of extra time would be played.
Calendar
Round
Date
Extra preliminary round
Saturday 3 September 1938
Preliminary round
Saturday 17 September 1938
First round qualifying
Saturday 1 October 1938
Second round qualifying
Saturday 15 October 1938
Third round qualifying
Saturday 29 October 1938
Fourth round qualifying
Saturday 12 November 1938
First round proper
Saturday 26 November 1938
Second round proper
Saturday 10 December 1938
Third round proper
Saturday 7 January 1939
Fourth round proper
Saturday 21 January 1939
Fifth round proper
Saturday 11 February 1939
Sixth round proper
Saturday 4 March 1939
Semi-Finals
Saturday 25 March 1939
Final
Saturday 29 April 1939
Qualifying rounds
Most participating clubs that were not members of the Football League competed in the qualifying rounds to secure one of 25 places available in the first round.
Advancing to the competition proper for the first time were Runcorn, Colchester United, Apsley and Street, while Lowestoft Town was doing so for the first time since 1926–27, Horden Colliery Welfare for the first time since 1925-26, and Chorley for the first time since 1899-1900.
Hayes was the only club to progress from the extra preliminary round to the first round proper, defeating Wycombe Wanderers, Yiewsley, Chesham United, Banbury Spencer, Southall and Newport (IOW) to secure their place in the main draw. However, Chelmsford City was the most successful non-league club this season, moving from the preliminary round to the fourth round proper and defeating Barking, Ford Sports (Dagenham), Crittall Athletic, Romford, Dulwich Hamlet, Kidderminster Harriers and Football League sides Darlington and Southampton in their history-making run.
The matches were played on Saturday, 10 December 1938. Four matches were drawn, with replays taking place in the following midweek fixture. One of these, Halifax Town vs. Mansfield Town, then went to two more replays before being settled.
The matches were scheduled for Saturday, 7 January 1939, although seven matches began at later dates. Eight matches were drawn and went to replays, with one of these requiring a second replay to settle the fixture.
The matches were scheduled for Saturday, 21 January 1939. Five games were drawn and went to replays, of which two went to a second replay. Chelmsford City was the last non-league club remaining in the competition, participating in their ninth round of this tournament.
The four sixth round ties were scheduled to be played on Saturday, 4 March 1939. There was one replay, in the Huddersfield Town–Blackburn Rovers match.
The semi-final matches were played on Saturday, 25 March 1939. Wolverhampton Wanderers and Portsmouth won their matches to meet in the final at Wembley.
As a result of the suspension of the FA Cup for the duration of the Second World War, the next FA Cup final was not until seven years later in 1946, thereby enabling Portsmouth fans to claim that their team has held the Cup for the longest time.