In his homily, the pontiff said families were the "bricks that build society".
The couples were all from Rome and included a man whose first marriage was annulled. A woman who had a daughter from a previous relationship while she was unmarried also tied the knot.
Roman Catholic teaching says sex outside marriage is a sin, but Pope Francis has stressed the importance of forgiving and not judging others several times.
He said that marriage was "real life, not some TV show" and that couples should expect to argue, but that Jesus' love would help them through.