Osborn was a decorated Navy pilot prior to serving as state Treasurer from 2006 to 2011.
He's likely to face a crowded primary for what looks to be a safe Republican seat. The presumed frontrunner, Gov. Dave Heineman, has decided against running, as has Rep. Jeff Fortenberry (R), eliminating two of the most prominent contenders for the race.
Osborn is likely to be joined in the primary by Midland University President Ben Sasse, who is launching a listening tour across the state this summer before he decides on running. Former Senate candidate Pete Ricketts could also run.
Democrats have yet to front a candidate for the seat.
Report: Former state Treasurer enters race for Sen. Johanns's seat
According to the Lincoln Journal Star, Osborn has filed a statement of candidacy with the Federal Election Commission and has hired Dave Boomer, a consultant for Rep. Lee Terry (R-Neb.), as his campaign manager.