Laura Walker said she believed in Boris Johnson's promise to "level up" the north of England and wanted to "hold him to it".
Ms Walker left the Yorkshire Party earlier this year having been appointed to its deputy leader in March 2019.
She stood against Normanton, Pontefract and Castleford MP Yvette Cooper in last year's General Election, having come within just over 300 votes of defeating Labour in a Wakefield Council seat at the local elections the previous May.
Ms Walker, who first joined the Conservatives while at university, said she'd had "no ideological fallout" with the Yorkshire Party.
But she explained she'd switched political allegiance in a bid to have more ability to "change things that aren't working" and to pursue cherished causes, such as more help for military families.
Ms Walker said: "I still have a lot of friends in the Yorkshire Party and I really wish them well. I think the people there are in it for the right reasons, and they're not trying to achieve anything I completely disagree with.
"But the things I'd like to achieve are very difficult within a small regional party.
"I supported devolution as a means of achieving some of the things I wanted to do, whereas for a lot of people it's an end of itself."
Ms Walker said her senior position within the party had been "an insight into how difficult a job leadership is", adding: "You have to balance driving things forward with keeping people happy and it's quite tricky."
"Within Labour, the Conservatives or the Lib Dems its impossible to have singularity of thought because there's so many members and so many different factions," she said.
"But if you have a party with only a few hundred members, any differences of opinion, even if they're academic, can be taken quite personally."
Ms Walker, who admitted having been previously frustrated with the Tory leadership's approach to the North, said she had confidence in the government to deliver more parity between regions.
Boris Johnson has said many of the General Election votes he received from former Labour supporters in Yorkshire and the north-east are "on loan" and must now be justified by the Conservatives.
Critics have dismissed the rhetoric for supposedly lacking in substance, with even former Tory minister Justine Greening citing last week's exams U-turn as evidence the government is "levelling down" instead.
But Ms Walker said: "It felt like under David Cameron there was a lot of talking to affluent people in the south-east and that irked me a bit.
"I'm originally from Manchester and I've seen what regeneration can do in Manchester. That needs to spread out everywhere.
"We've got smaller towns that feel ignored and need to feel like they have attention from government.
"I wouldn't say my support is conditional or on loan but I'd say me rejoining is about making sure that gets delivered.
"I want to hold Boris Johnson to that promise of giving the North greater equality with the South."
Local Democracy Reporting Service