Landnámabók, the Book of Settlement, tells of two farms on the site of Garðabær: Vífilsstaðir and Skúlastaðir.

The town is also home to Marel hf., the largest company on NASDAQ OMX Iceland by market capitalisation.[when?

The town's main sports club is Stjarnan, best known for its men's football team that plays in the Icelandic Premier League and won the competition for the first time in 2014.

Award-winning dancer Hanna Rún Óladóttir and strength athlete Páll Logason live in Garðabær.

Brothers Ómar and Óskar Guðjónsson of ADHD, as well as Ragnheiður Gröndal, all hail from the town.