In 1934 the central section was rebuilt seven storeys high, with a sub-basement for control gear, boilers, emergency generators etc., especially designed not to interfere with the Magic Cave.

They had business links with other major regional department store retailers (Sydney's Grace Bros and Tasmania's FitzGerald's) with joint ownership of the Intercontinental Buying Group.

Ultimately, this chain was sold, and it operated under separate ownership until 1994 (when it closed due to financial problems – unrelated to John Martin's).

Also, the discount store phenomenon was gaining momentum, with Kmart and Target expanding rapidly, and the establishment of Big W. Another pressure was the increased availability of bank credit cards.

Ultimately, ownership settled in 1985 when the Adelaide Steamship Company-controlled David Jones acquired John Martin's.

During the mid-1990s, John Martin's operated in the face of more aggressive competition, including the continuing rise of discount department stores, and the expansion of local competitor Harris Scarfe (which expanded from its Rundle Mall base into suburban Adelaide locations).

John Martin's endeavoured to relaunch and counterattack, with a new logo in early 1994 and publicity of a price match policy.

However, these measures did not improve sales and profit, The stores at Elizabeth Shopping Centre and Westfield Arndale were sold to Harris Scarfe.

The stores at Westfield Marion and West Lakes Mall were rebadged as David Jones in late October 1996.

Soon after, the Art Deco building was demolished to allow for the Adelaide Central Plaza complex which was to house a new smaller David Jones store and other retailers which opened in August 2000.

Since the closure of the stores, David Jones have returned ownership of the John Martin's name to the Hayward family.

John Martin's had a dedicated area set aside each year for the Magic Cave which was located next to the toy department and was surrounded by Christmas decoration and trim.