In the UK, social media marketing spending will hit €816.5m in 2017, up from €391.6m, the latest forecast from Forrester has found.
The report also predicts that social media marketing spending in Europe will reach €3.2bn in 2017, up from €1.4bn in 2012; and that as social networks mature, defining the individual ROI of social media marketing will get harder.
However, Forrester warns that the predicted growth is under threat of new European privacy legislation which it expects to take effect in 2016 and could cut the predicted social media marketing spending growth by more than €880m.
James McDavid, researcher at Forrester, said: "The full extent and implementation of the European privacy legislation is as yet uncertain, and the fractured manner in which such directives are applied across various European countries means that compliance costs for marketers will rise.
"We do know, though, that the legislation will require the implementation of a 'right to be forgotten,' with increased fines for noncompliance. As a result, we believe that when the legislation comes into force in 2016, it will depress spending on social media marketing by around €401.9m in 2016 and €481.7m in 2017."
The research also predicts a growth in the number of users on social media channels: suggesting that in 2017, more than 70 per cent of the online population in Western Europe will be engaged on social media, up from 63.4 per cent in 2013.
The figures for the UK are expected to be higher than the European average, hitting 77 per cent in 2017.