The 1977–78 Yorkshire Cup was the seventieth occasion on which the Yorkshire Cup competition had been held. This year, for the first time for eighteen years (and the last time in the history of the Yorkshire Cup), a new name appeared on the trophy, with Castleford winning it by beating Featherstone Rovers in the final by the score of 17-7. The match was played at Headingley, Leeds, now in West Yorkshire. The attendance was 6,318 and receipts were £4,528. It as also Featherstone Rovers's second consecutive Yorkshire Cup final appearances, both of which resulted in a defeat.

The Rugby Football League's Yorkshire Cup competition was a knock-out competition between (mainly professional) rugby league clubs from the county of Yorkshire. The actual area was at times increased to encompass other teams from outside the county such as Newcastle, Mansfield, Coventry, and even London (in the form of Acton & Willesden).

The Rugby League season always (until the onset of "Summer Rugby" in 1996) ran from around August-time through to around May-time and this competition always took place early in the season, in the Autumn, with the final taking place in (or just before) December (The only exception to this was when disruption of the fixture list was caused during, and immediately after, the two World Wars)

This season there were no junior/amateur clubs taking part, no new entrants and no "leavers" and so the total of entries remained the same at sixteen. This in turn resulted in no byes in the first round.^[1]

1 * Headingley, Leeds, is the home ground of Leeds RLFC with a capacity of 21,000. The record attendance was 40,175 for a league match between Leeds and Bradford Northern on 21 May 1947.

• 1977–78 Northern Rugby Football League season
• Rugby league county cups