A tributary of Willoughby Falls Creek ran across the site in the current location of the Music Shell and there was also a swamp near the existing Fig Tree Lane.

[2][1] In 1894, the Acting Under Secretary of Lands approved two areas for the playing of cricket and football totalling 2.3 hectares (5.7 acres) as well as a five-year licence for over 2,000 milliseconds (2.0 s) for a bowling club.

This fountain, however, was subsequently re-located to Civic Park between Stanton Library and the North Sydney Council Chambers in 1982.

Originally designed to vent the reticulation system that took waste water from North Sydney and Mosman, it was located within St Leonards Park until it was separated by the construction of the Warringah Expressway.

The foundation stone was laid in 1924 for an Art Deco style 13-metre (43 ft) cenotaph made of Bowral trachyte and was unveiled in 1926.

[1] In 1948 the Music Shell, designed by Peddle Thorp and Walker was completed and officially opened on 13 November by the Honorable Clive R Evatt, Minister for Housing with an audience of 4000 watching to a performance by the Sydney Symphony Orchestra and the North Shore Choral Society.

[1] A brick wall was constructed around North Sydney Oval during 1936, resulting in the removal of a double avenue of Moreton Bay figs along the Miller St frontage.

Queen Elizabeth II and Philip, Duke of Edinburgh drove through St Leonards Park in front of 48,000 school children on 18 February 1954.

Grass netball courts were constructed during the 1960s to the south of the bowling club near Ridge St for use primarily by local schools.

[1] In 1960, the North Sydney Leagues Bowling Club was granted a special lease 1960/227 for perpetuity to exclusive occupation upon the Crown Land.

[1] On 10 February 1984 there was a land exchange involving North Sydney Council exchanging the car park (532.6 sq.m) to the south of the bowling club houe[4] for equal areas of land to the north and east of the bowling greens[5] to be transferred back to being part of St. Leonards Park.

A 42.2-kilometre (26.2 mi) blue line was painted along Miller St to mark the course of the Marathon, across the Sydney Harbour Bridge, to finish at the Olympic Stadium.

[2][1] In September 2016 the NSW Land & Environment Court upheld an appeal against North Sydney City Council's deemed refusal of DA78/16 for the internal refurbishment of the main bowling club house; to provide extra toilets; continued use of part of the most-northern green and specify hours of operation and patron no's for the NSBC subject to conditions.

[2][1] In 2018 it was announced that North Sydney Council would commence an upgrade of the park including improving the war memorial with a reflection pool, restoration of the Tunks Fountain and elevation on a new plinth, new benches, picnic tables, barbecues and drinking fountains, upgrades to lighting, additional tree planting, and an expanded playground.

[1] Other architectural features of note include:[1] A few dead tree stumps have also been retained for their habitat value for nesting sites of the local parrot species and possums.

The War Memorial and Tunks Fountain are in good condition however, the setting has been cluttered by light poles and an enclosing wall extension to the North Sydney Oval complex.

[1] The North Sydney Sewer Vent was originally located within St Leonards Park, however it was separated by the Falcon Street exit ramp when the Warringah Expressway was constructed in the 1960s.

[1] The site is of state heritage significance as a rare and representative example of a largely intact Victorian era park designed in the gardenesque style with its original layout still appreciable.

The post WWII music shell and Modern movement style Bowling Club are rare surviving examples of these types of structures.

[1] St Leonards Park was listed on the New South Wales State Heritage Register on 31 July 2015 having satisfied the following criteria.

The park has state significant associations with Mr Edgar Herbert a noted pioneering specialist in physical education.

He was also a valued supervisor of Playgrounds to the Kindergarten Union, a colleague of Walter Burley Griffin and actively involved in the Castlecrag Progress Association.

In the 1940s Herbert was Principal of the Leadership Training College which staffed the playground and implemented a program of dance and drama activities as well as sporting events.

[1] The place is important in demonstrating aesthetic characteristics and/or a high degree of creative or technical achievement in New South Wales.

The park also includes distinctive examples of early 20th century architecture including: the Bob Stand which was relocated to St Leonards Park from the Sydney Cricket Ground in the 1980s, the WWI Memorial, a fine example of an Interwar Stripped Classical WWI Memorial, designed by Frank Thorpe and the Music Shell designed by Peddle Thorp and Walker in the Art Moderne style.

The 1960s Bowling Club is a good and intact example of Modern Movement architecture applied to a popular leisure activity.

St Leonards Park has a high level of local social significance as a recreational facility for cricket and various forms of football.

The site is of state heritage significance as a rare and intact example of a Victorian era park designed in the gardenesque style with its original layout still appreciable.