O'Connor has moved to the League One outfit after being released by Derby County, and Smith has revealed that the Saddlers beat a number of sides to secure the signing of the versatile defender.
The 43-year-old is quoted by the Express & Star as saying: "We've signed an extremely reliable and solid defender. I played alongside him at Port Vale and he's worked with Richard O'Kelly for a number of years, so we know the character that he is and what he'll bring.
"There were a lot of teams interested in him, but I'm delighted that he's chosen to come here. It certainly is a big bonus for us."
O'Connor is returning to the West Midlands after beginning his career with Aston Villa.