The Ravens traded Boldin to the San Francisco 49ers for a sixth-round draft pick in the off-season.
The 32-year-old enjoyed an excellent debut for his new side in their win over the Green Bay Packers.
Harbaugh told reporters: "He's a great player, and there's nobody here that didn't want him back. It was a business decision both ways."
The Ravens face the Cleveland Browns in week two of the new NFL season.