— Valencia CF (@valenciacf_en) August 6, 2014
Mustafi, 22, part of Germany's triumphant squad at the World Cup finals in Brazil, will undergo a medical and be presented to the media on Thursday, Valencia said on their website (www.valenciacf.com).
Mustafi, whose parents are Albanian, came through the youth academy at Bundesliga club Hamburg SV and had a stint at English Premier League side Everton before joining Sampdoria in 2012. He made his debut for Germany in May and has four caps, his last appearance coming in the World Cup last-16 match against Algeria.
Valencia are in the process of being taken over by billionaire Singapore businessman Peter Lim, raising hopes they can mount a serious challenge to wealthy Spanish rivals Real Madrid and Barcelona, the world's richest clubs by income.