In 1905 Ilford were founder members of the Isthmian League, which their treasurer George Clarke had played a key role in establishing.

The club won the London Senior Cup for a third time in 1913–14, defeating Nunhead 2–0 in a replay after the initial final ended 1–1.

The club went on to finish as league runners-up in 1926–27, and reached the second round of the FA Cup again the following season, losing 5–3 at Exeter City.

In 1928–29 Ilford reached the final of the FA Amateur Cup, going on to beat Leyton 3–1 at Highbury in front of a crowd of 35,000.

However, after the first match at Crystal Palace against Casuals ended in a 1–1 draw, they lost the replay at Upton Park 2–0.

In 1973–74 the club reached the final of the last edition of the FA Amateur Cup, losing 4–1 to Bishop's Stortford at Wembley.

However, issues including a lack of finance, manpower and home ground led to the club leaving the league in 1990.

[2] However, after being given notice to leave the site in 1904 as it was to be used for housing, the club leased four acres of land to the north of Ilford, where the ground that became known as Lynn Road was built.

[2] Lynn Road was used for FA Amateur Cup semi-finals, and during the 1948 Summer Olympics to host two matches in the football tournament.

After reforming, the modern Ilford struggled to secure a permanent ground, groundsharing at Barking East Ham United and Southgate Olympic, as well as playing at the Douglas Eyre leisure complex in Walthamstow and two matches at the council-owned Cricklefield Stadium in 1989.