The Belgian midfielder is due to undergo a medical on Monday after the Clarets agreed a £7.5m fee with Anderlecht for his services late last week.
Defour is understood to have already agreed personal terms with the Premier League new boys and will become their record signing.
The 28-year-old has won 46 caps for Belgium but was not included in the squad for Euro 2016.
Defour was wanted by Manchester United in 2011 after starring for Standard Liege in his homeland but a deal did not materialise.
He went on to join Porto and won the Portuguese league twice during a three-year spell before returning to Belgium to join Anderlecht in 2014.