McNulty, 23, has put pen to paper on a season-long loan deal at the Northern Commercials Stadium. Parent club Sheffield United have the option to recall the striker in January.
He will wear squad number 18 this season.
Subject to the club receiving the relevant clearances, McNulty will now be in contention for City's Sky Bet League One fixture at Millwall this Saturday.
The Scottish forward enjoyed a profitable loan spell with League Two side Portsmouth last season, netting twelve times for Pompey from November onwards.
McNulty actually has a commendable scoring record throughout his career so far having reached double figures for every season he's played in since 2011.
The proven scorer netted thirteen times for Sheffield United during his first season with the Blades following his move to Bramall Lane in the summer of 2014.
McNulty also scored nineteen times for Livington in the Scottish Championship in the 13/14 season, form which earned him his move south of the border.
Speaking about the move to City, McNulty said: "I am excited to join a big club like Bradford.
"I had a few options but I always wanted to come here once I knew of their interest.
"With the size of the club, the manager and the fan-base here, it was a no-brainer.
"I spoke with a lot of people who have worked with the manager before and they all spoke very highly of him.
"I can't wait for the opportunity to work with him, hopefully it will benefit me and the club.
"I've played here a couple of times before with Sheffield United and one thing that always stood out was the size of the crowd and the atmosphere.
"I'm raring to go and I can't wait for the gaffer to give me an opportunity."