Walker said he was relieved at the final whistle and for the team to collect their first points of the season.
"The boys really listened to me because they came out really strong from the start," he said. "I couldn't have been more stoked with the win. It really could have gone either way in that second half. It was a very tough, good game and in the end I think it came down to who wanted the result more.
"It was so important for us to get an early victory in the league. You always want to make your home your castle."
Walker said striker Smith, on four goals for the season and returning to the club after a four-year break, was a standout.
"I'm very impressed with what I've seen from him so far," he said. "He's very strong on the ball and great at holding it up. He's been away for a while but he's certainly making up for that at the moment."
The result leaves United seventh in the table and they face a tough game next weekend when they take on third-placed Otumoetai FC, at home for the third weekend in a row.
"Everyone is on a high right now," said Walker. "We need to keep this confidence going because it certainly will be a tricky next match."
Loaded WaiBOP Premiership results:
Rotorua United AFC 2 Tauranga Old Blues 1
Otumoetai FC Edmonds 2 Judd Te Awamutu 2
Melville 5 Matamata Swifts 3
Cambridge FC 7 Papamoa Football Club 0
Tauranga Boys' College 1st XI 1 Taupo AFC 2
West Hamilton United 3 Waikato Unicol Premiers 1
Loaded WaiBOP Championship results:
Rotorua United AFC 1 Tauranga Old Blues 0
Otumoetai FC 1 Edmonds Judd Te Awamutu 0
Cambridge FC 1 Hamilton Wanderers 0
Tauranga City 2 Taupo AFC 1
Te Puke United 0 Waikato Unicol Reserves 0
Tokoroa AFC 4 Matamata Swifts Reserves 1