A graduate of the Ajax academy, the 22-year-old has played for Ajax, NEC Breda and Roda JC in the Dutch first division.
He has signed with the A-League side for two years.
"This is exactly what we wanted. We wanted a defensive player who is comfortable in midfield, at centre back when we lose players to the All Whites and at fullback if we need him to fill in," Merrick said.
"That allows us to do what we did with Rodriguez-Gorrin and get him forward into goal scoring positions.
"Bonevacia will complement our team. He is exactly what I was looking for. To get a 22-year-old is just an exceptional signing.
"It gives me that very important cover for Albert Riera which caught us out last year."
Bonevacia, who spent almost 10 years coming through the ranks at Ajax, takes the final import spot for the Phoenix.
But Merrick stressed that did not mean that injured, off-contract playmaker Paul Ifill would not be returning to the club.
"Paul will be given every opportunity, with our help, to get fully fit. And when he gets fully fit and ready to go we'll find a way to get Paul in the team as well," Merrick said.
"I've spoken with Paul. He was one of the first calls I made when we got this signing over the line. Paul is very much in our plans. His job is to get himself fit."
The Phoenix are also still waiting on a decision from Football Federation Australia before they can officially sign midfielder Michael McGlinchey.
Merrick has refused to make further comment on that ongoing saga after blasting the FFA on Thursday for not having resolved the situation so far.
Wellington sign Dutch youngster
