Villa say that, subject to medical clearance, a deal will be concluded with Eredivisie runners-up Feyenoord for Vlaar next week.
The 27-year-old centre-half will undergo a medical next week in Birmingham before a potential three-year deal can be formalised.
Vlaar is primarily regarded as a centre-back and will provide competition for James Collins - reported to be a target for his previous club West Ham - and Richard Dunne.
He made his breakthrough at senior level in Holland with AZ Alkmaar before moving to Feyenoord in 2006.
Vlaar has formed a solid partnership with Brazilian defender Andre Bahia in recent seasons.
He helped Feyenoord to qualify for next season's Champions League after they finished runners-up in Eredivisie for the 2011-2012 campaign.
New Villa boss Paul Lambert has already recruited right-back Matthew Lowton from Sheffield United as he looks to bolster his defensive options for the new campaign.
Source: PA
Source: PA