Tucker went 5 for 5 on field goal tries during Baltimore's first five preseason games and showed more leg strength than the 32-year-old Cundiff. Tucker made two field goals of 50 yards or longer; Cundiff was 1 for 6 last year from that distance.
He also comes at a cheaper price.
Cundiff's place on the roster appeared in peril after coach John Harbaugh used Tucker for all the placekicking chores in Thursday night's preseason win over Jacksonville.
Tucker was invited to camp as an undrafted free agent to challenge Cundiff, who made the Pro Bowl in 2010 but last season missed a potential game-tying, 32-yarder against New England in the waning seconds of the AFC title game.
Harbaugh liked the way Cundiff rebounded from the pivotal miss, but decided Tucker was simply the better choice for Baltimore in 2012.
"These decisions are never easy, and this one was difficult for all of us," Harbaugh said. "Billy had a great camp, the best he has had with us. He showed, like he always has, a toughness and an ability to come back and be a top flight NFL kicker."
After Friday's game against the Lions, Cundiff insisted he had done everything possible to put that miss against the Patriots behind him.
"Let's be honest, I feel like I've been through enough," he said. "There's not a single thing that I think somebody can trap me that I'm not prepared for. So, I know my confidence has been high, I know when I came into training camp a lot of people asked me where my head was at and kind of questioned whether I'd be able to even kick. Whatever the case may be, I felt like I proved continually throughout training camp that I came in prepared. And regardless of what's thrown at me, what the situation is, I feel like I'm ready to kick."
Tucker, a standout at Texas, believes he's become an even better kicker during training camp.
"To the naked eye, it doesn't look like I've made a lot of changes, but I've made a complete transformation from the kicker I was in college to the kicker I am today," he said Friday. "I feel like I'm kicking the best I ever kicked."