The 28-year-old scored over 50 goals in just under 250 appearances for Scottish side Hearts but would have been out of contract this summer.
That sparked interest from clubs in Scotland but Walker was keen to test himself south of the border again, having previously had spells at Peterborough United and Wigan Athletic.
It has been a frustrating first half of the season for Bradford, with the club six points outside the play-off places.
The Bantams are one of the best supported sides in League Two and the size of the club was one thing which attracted Walker to West Yorkshire.
He said: “As a football player, you always want to play for big clubs. I did have a few offers back home in Scotland but when I heard Derek Adams wanted to bring me here, it was a no-brainer.”
Walker has no problem shouldering the expectations on him at Valley Parade.
Hearts and Bradford have had a similar average home attendance in recent years, so Walker is not phased by playing in front of the Bradford faithful.
He continued: “The big expectations and the big fanbase is something I am used to .
“Hopefully, I can take it on my shoulders and produce some good performances.”
Walker is in line to make his debut for the club this afternoon as Bradford welcome Salford City to Valley Parade. The fixture is an opportunity for Adams’s side to leapfrog Salford, who sit two points above them in the table.
Walker is hoping to bring more goals to Bradford, adding: “I am not the most vocal on the pitch, I like to do my talking in front of goal and with the ball.
“Hopefully I can produce a few goals for the team, I think it is something they have struggled with in the last few weeks, so that’s what I am looking to do.
“As a forward player you are always looking at goals and assists. I am looking forward to Saturday, and hopefully getting off to a good start.” Walker scored on his last appearance in Bradford, as he netted the winning spot-kick in an FA Cup second round replay penalty shootout for Peterborough. The goal does not count towards his career tally but he is determined to find the net plenty more times at Valley Parade – now that he will be doing so in a Bradford shirt.