Earlier this month, Bryant quietly issued his proclamation, saying people should "earnestly strive to understand our heritage."
A spokesman for the governor said his predecessors from both major parties have made similar proclamations.
"Gov. Bryant believes Mississippi's history deserves study and reflection, no matter how unpleasant or complicated parts of it may be," Clay Chandler said. "Like the proclamation says, gaining insight from our mistakes and successes will help us move forward."
News of the proclamation fueled a mostly negative reaction on social media Thursday.
Bryant said in his proclamation that April was selected because it is the month "the Confederate states began and ended a four-year struggle."
According to the Clarion-Ledger newspaper, Bryant issued a proclamation in 2012 using almost the same wording.
The proclamation is not listed on the governors' website with other recent decrees. The website has a page for groups to request proclamations, and the Jackson Free Press reported that Chandler told a reporter the Mississippi Division Sons of Confederate Veterans asked for the decree.
A post last week on the group's Facebook page announcing the proclamation said: "It is official in Mississippi, April 2016 Confederate Heritage Month. Remember and honor the memory of you Confederate ancestors this April." The post has been liked 241 times.
The proclamation came as the Mississippi Legislature was going through 19 bills dealing with changing or keeping the state flag, the last one in the nation to feature a Confederate battle flag emblem. CNN affiliate WAPT
reported there will be no changes, because Tuesday was the deadline for legislative committees to act on general bills.
"I think that the Legislature is shirking its responsibility as a legislature to deal with the issue. It's been dealt with in every state in this country except Mississippi," John Horhn, a state senator from Jackson, told the station.
Bryant, a Republican, easily won re-election in November.