Bouchard, who lost to Petra Kvitova in the 2014 final, won her last match in the preliminary rounds 6-3, 6-2 against Mariana Duque-Marino on Thursday. The Canadian is ranked 191st.
In February, Bouchard settled a lawsuit against the U.S. Tennis Association related to a concussion she said she got when she fell in a locker room at the 2015 U.S. Open.
Zvonareva, beaten by Serena Williams in the 2010 Wimbledon final, got past 19-year-old American Caroline Dolehide 6-2, 6-3 in qualifying Thursday.
The 33-year-old Zvonareva, also the U.S. Open runner-up in 2010, has not played in a main draw at any Grand Slam tournament since the Australian Open in 2015. She last competed at Wimbledon the year before that.
In another qualifying match, 18-year-old American Claire Liu beat Nicole Gibbs 6-4, 6-3 to reach the Wimbledon main draw for the first time, a year after winning the junior title at the grass-court major.
Stephane Robert, 38, became the second-oldest Wimbledon qualifier in the Open Era since 40-year-old Neale Fraser in 1974.
Ruben Bemelmans tied the Open Era record by qualifying for the fifth time.