The 37-year-old Canadian singer and his 25-year-old Argentine actress wife were married in 2011.
The couple met in 2009 during a South American concert tour.
A representative for Buble confirmed that the couple are expecting.
Buble is a Grammy-winning pop singer who has sold millions of albums, including Crazy Love and 2011's Christmas. Lopilato made her name as a model and in Argentine sitcoms and soap operas.
The famous heart-throb, who was on the Saturday Night Show recently, has just announced that he'll perform a massive five nights in the O2 Dublin next year.