Walter, signed by the Patriots on Aug. 3 four days after he was waived by Oakland, appeared to have made the team as Brady's backup when the club let go of Kevin O'Connell earlier in the week.
But the club elected to cut him free.
"I think Andrew had a lot of positives, and we talked about those when we signed him, and I think they still exist," coach Bill Belichick said in a conference call with the media Friday afternoon. "In the end we still made decisions that are in the best interest of the football team."
Hoyer, a free agent from Michigan State, played the entire game in New England's 38-27 comeback win over the New York Giants on Thursday night.
Seen as a long shot early in camp, he capitalized on his last chance in the exhibition finale, leading the Patriots from a 21-point first-quarter deficit by completing 18 of 25 passes for 242 yards and no interceptions, although most of that was against backups.
"Not bad," Belichick said after the game. "He handled the ball fairly well, threw it accurately."
Hoyer threw for one touchdown and led drives that ended with BenJarvus Green-Ellis rushing for three scores.
When asked if the team will go with only two quarterbacks for the opener on Sept. 14 against Buffalo, Belichick didn't rule out the idea, but also said they'd look at who else may be let go.
"That's really a hard question to answer," he said. "We'll have to wait and see what our options are, not only what players are available, but also in terms of how we want to manage our roster. There's so many moving parts to the process, with difficult positions and the overall makeup of the team and looking at the active 45-man roster, then the different players that might or not be available throughout the league."
Teams are required to have their rosters trimmed to 53 by Saturday.
The team also cut seventh-year linebacker Vinny Ciurciu, sixth-year guard Billy Yates, first-year receiver Robert Ortiz, third-year safety Roderick Rogers, and second-year defensive lineman Stephen Williams.