Greystones has experienced a huge increase in its population since the 1970s with the construction of mainly large housing estates. The first of these periods lasted for around a decade seeing the development of estates like Hillside, Applewood Heights, Redford Park and many other smaller ones like Burnaby Park. The second boom in construction came during the Celtic Tiger period of the early 2000s which saw developments such as Charlesland (the biggest) just south of the town, which includes over 1,000 dwelling units. Following the 2008 financial crisis little development took place, evident in the difference from the 2011 to 2016 census'; an increase of only 1000. This is compared to previous increases like 2006 showing 3000-4000 in growth. Other projects such as the harbour redevelopment stalled or completely halted during this time period.

As of 2018, Greystones was experiencing a housing boom. A number of large-scale developments were taking place, mainly of the western fringes of the town, in the harbour area and around Charlesland.[citation needed] The main schemes included Seagreen and Waverly in Blacklion, Glenheron beside Charlesland and Marina village at the harbour. These equate collectively to over 1000 dwellings under construction.[citation needed] There are also multiple other similar schemes approved or pending approval.[3][4] Greystones is the only town in County Wicklow with this scale of growth.

As of the 2016 census the population of Greystones town stood at 18,140 while the Greystones Municipal District Population stood at 26,323 making it the second largest town in the county after Bray.

Wicklow County Council and Greystones Municipal District Council plan for at least 24,000 by 2028 in the town itself.

Along with the housing developments, road networks and facilities have been "improved" to cater for the growth. The road between Greystones and Bray has been slightly widened and realigned. A dual carriageway link road (R774) connecting Greystones to the N11 has been completed to the south of the town. Construction of a full interchange with the N11 has also been completed. Chapel Road has been connected with Blacklion Manor Road forming a new section of wide higher capacity road from the junction at Lidl to the junction with the top of Applewood Heights, creating a complete bottleneck at Delgany village. Estates like Seagreen access from this road.

According to the 2016 census, Greystones has the largest Church of Ireland presence as a proportion of the population (8.2%) anywhere in the country, has the largest proportion of Protestants overall (10.5%), and is the least religious town in the country (18.3% 'no religion').