At the back end of the 20th century the club fell into financial difficulties following a two year spell in the Sheffield Alliance, and had to miss out the 1898/99 season, but they were back a year later and again reached the final of the Hatchard League, this time feeling the bitter taste of defeat after losing the play-off final.
For the first time they also entered the Portland Charity League, the chief competition run in the Worksop area, and they would win the the trophy in 1902 and 1903, before making it a hat-trick in 1904 by winning the Portland Charity Cup, the league having changed to a knockout competition. Although Hatchard League honours deserted the club throughout the 1900s and 1910s (the club played sporadically throughout World War I), the Portland and Aston Charity Cups were won with regularity.
In the summer of 1920, the club committee took the decision to enter the FA Cup for the first time, and after dispatching Anston United in the Extra Preliminary Round, old rivals Worksop Town lie in wait next. The Great Central Railway company laid on extra trains to take the hundreds of Kivetonians to the game, and it took a late goal by the Midland League outfit to shatter their hopes of further progression in the old competition – Worksop eventually losing out to Bristol Rovers in the last round of qualifying.
By now the club was based on Hard Lane, with Sheffield Wednesday opening the new dressing rooms and pavilion by playing a friendly match. Initially, only the pitch nearest Hard Lane was used – it wasn’t until the 1960s that the first team moved to the pitch it uses today.
The club’s best run in the FA Cup came in 1922. After beating Ardsley Athletic, Maltby Main and Treeton Reading Room in the early qualifiers, Park came up against another Midland League side, Rotherham Town, in the 3rd Qualifying Round. Again hundreds of Parkites made the journey to cheer on their team and again the team lost to the only goal of the game – Rotherham lost out to Halifax Town in the next round, and two years later merged with their rivals Rotherham County to form Rotherham United.
That season saw the sad demise of the old Hatchard League, with Park spending their remaining pre-WWII years in Sheffield league competitions such as the Minor League (which they won in 1924), the Amateur League, and the Association League, which was considered the strongest in the area and would merge with a revived Hatchard League in the 1980s to form the present day County Senior League.
Kiveton also spent a few pre-WWII seasons in the Holbrook & District League, which was based around the Killamarsh and Beighton area, with Kiveton winning both the league and league cup in 1937.
After the outbreak of the Second World War, football in the country understandably took a back seat, with many non-league clubs laying dormant, or even going out of existence altogether. For Kiveton, it was fortunately only the latter, with the club returning to league action as early as 1942, when they entered the Worksop & District League.
When hostilities ended, the club re-entered the Association League, and after finishing inside the top six for the first time, they were invited to take part in the Sheffield Invitation League, a short lived end of season competition. Park came through the group stage and beat Sheffield United reserves in the semi-final at Hard Lane, but were beaten 3-5 in a thrilling final against Thurnscoe at Worksop. Kiveton also reached the semi-final of the Sheffield Senior Cup for the first time to end a memorable campaign.