Dexter made the announcement Wednesday after meeting with the Nova Scotia School Counsellors Association.
"Schools are about learning development, they are about academic achievement, but increasingly they are about the social development of our children," said Dexter.
"This recognizes the important components that go into that development."
About $9.4 million will go towards hiring mental health workers and youth health centre co-ordinators in schools.
The remaining $4.6 million will allow school boards to add 51 guidance counsellor positions, up from the 195 counsellors currently working in Nova Scotia schools.
Dexter said this will raise the ratio to one counsellor for every 500 students, fulfilling one of the key recommendations in a 2012 report from the Nova Scotia Task Force on Bullying and Cyberbullying.
"With declining enrolment over the next couple of years, we might actually be able to even have a higher ratio than announced today," said Education Minister Ramona Jennex.
Any kind of new money targeted for school counsellors is a step in the right direction, said Teri Cochrane, president of the Nova Scotia School Counsellor Association.
"Positive pro-social skills can be taught," she said. "And for students that don't have that capacity, we can build that by looking at social thinking, empathy development, emotional self-regulation — those are the sorts of things that counsellors can provide in the school."
As for the $9.4 million earmarked for improving mental health support systems, that funding would double or even triple the number of clinicians in schools, said Patricia Murray, a special adviser on mental health and addictions strategy with the Ministry of Health.
Jennex said the government is still discussing with school boards how that funding will be used to support school-based clinicians and health centres.
There are currently 48 youth health centres operating in Nova Scotia schools. There are about 180 junior and senior high schools in the province, according to the Education Department.
The funding will be available for the 2014-15 school year, which would come after a provincial election.
Opposition parties criticized the government for not approving the funding earlier.
"Who knows how many kids could have been helped ... if the NDP had acted sooner," Progressive Conservative critic Eddie Orrell said in a statement.
The Liberals also condemned the delay, accusing the government of refusing to act until forced to do so because of public pressure.