A proposed merger with Solna in 1971 was never implemented, making Sundbyberg, with an area of 8.83 square kilometres (3.41 sq mi), the smallest municipality in Sweden, but also the most densely populated.

Sundbyberg was for a long time only an area of small agriculture value and most of all used as a place to spend summer for rich families in the city.

In 1863 almost the entire area was bought by Anders Petter Löfström, including Duvbo Estate, who began building houses there.

A. P. Löfström also donated to the municipality, all land for roads, streets, parks, school, church and other public areas.

Sales of land was aimed at workers and industry, and the relative lack of public services caused a strong cooperative spirit to form.

Rising housing prices led to a more densely built suburb than envisioned in the city plan,[7] as well as cause Sundbyberg to rapidly lose its industrial character.

[3] Since the 1950s when Storskogen was built, Sundbyberg has expanded one district each decade, with Ör built in the 1960s, Hallonbergen and its metro line (which also serves Storskogen and Ör) in the 1970s, Rissne and its metro line (which also serves Central Sundbyberg and Lilla Alby) in the 1980s, Brotorp and Stora Ursvik in the 2000s.

[4] The most common professions for people working in Sundbyberg are (in order from most employed): IT developer, banker, human relations, secretary, business seller/purchaser, accountant, retail clerk, truck/bus driver, teacher, tax collector.

The Tvärbanan light rail service was extended from Sickla Udde via Alvik to Solna centrum in October 2013.

The line runs through Central Sundbyberg with tracks laid in the street and has two stops within the municipality.

Construction of a northern light railway branch from Ulvsunda to Kista that will pass through Rissne and Stora Ursvik started in 2018.