The pair tied the knot at the Parish Church of St Mary's in Easebourne, West Sussex, near their home in Midhurst.
Doctor Who star David Tennant, Fox's Lewis co-star Kevin Whately and Piper's ex-husband Chris Evans were among the guests at the wedding.
Fox's father and uncle, the actors James and Edward Fox, also showed their support.
Piper, 25, arrived at the venue in a low-cut ivory wedding dress hidden by a black overcoat . She was followed by four bridesmaids wearing short purple dresses.
The 29-year-old groom thanked photographers who wished him luck as he walked to the church with friends 45 minutes before the service.
The couple met last December when they performed together in Christopher Hampton's play Treats.
It was recently reported that Piper's parents rowed with their daughter over her decision to invite Evans to the wedding.