Tomlinson will assume co-ownership alongside former chairman John Ryan after contracts were finalised on Tuesday.
With completion set for July 18, Tomlinson and Ryan are to work with manager Paul Dickov on transfer targets and on-field business ahead of the new season.
Tomlinson, who hails from Doncaster, featured for the club in a reserve game earlier this year and had been linked with a takeover for a number of months.
"For me, this is all about the football, the community and restoring the excitement and desire to making Doncaster Rovers the most exciting club to play for in Yorkshire," said Tomlinson.
"I want to see the Doncaster Rovers supporters get the club the success it deserves. I grew up in Doncaster and have felt the love for football run through the town, it's for that reason that I have a real personal passion to make Doncaster Rovers a success story.
"This is a big step which I believe will open up opportunities to provide a very, very exciting future for the club and its supporters."
However, it seems likely to be Ryan who will do much of the hands-on work at the Keepmoat Stadium, with the 64-year-old having been chairman of the club for several years prior to stepping down in November - six months before the club were relegated from the second tier.
He was in charge as Doncaster rose through the divisions from non-league football to the Championship.
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