The investigation is in response to a complaint filed last month by the liberal American Democracy Legal Fund.
The group cites reporting by the Kansas City Star, which obtained records that show out-of-state political consultants that went on to work for Hawley's Senate campaign also advised his staff in the attorney general's office.
The records show campaign consultants gave direct guidance and tasks to Hawley's state staff.
Legal Fund President Brad Woodhouse in the November complaint wrote that it appears Hawley misused state resources "by instructing political consultants to direct state, taxpayer-paid staff to undertake tasks that would raise Hawley's profile in his bid to represent Missouri in the U.S. Senate."
"Josh Hawley's flagrant abuse of his taxpayer funded office for his own political gain deserves immediate investigation," Woodhouse said in a Thursday statement. "We're heartened to see Secretary of State Ashcroft give this racket further scrutiny."
Attorney general spokeswoman Mary Compton said in a statement that the office is "delighted" to cooperate with Ashcroft's investigation and "put these ridiculous allegations to bed once and for all."
"These allegations are totally meritless and nothing more than a partisan attempt to slander the work of the Attorney General's Office," Compton said. "As we have said before, no taxpayer resources were ever expended for campaign purposes. And no government employees ever participated in campaign or political activities."
Hawley unseated Democratic U.S. Sen. Claire McCaskill last month. He'll assume office in January.