Malone and DeBoy, Democrats who represent District 12A, made independent announcements.
Malone, 55, a retired Baltimore County firefighter, has been in the House of Delegates since 1994 and DeBoy, 57, a retired Baltimore County police officer, was elected in 2002.
"After serious and careful consideration, I have decided not to seek reelection to the Maryland House of Delegates in 2014," Malone said in an email.
A few hours earlier, DeBoy announced his retirement in a phone interview, and he stressed that he and Malone made their decisions independently.
"I made my decision way before him," DeBoy said. "I've been mulling it over for a while.
"I started looking at it and said, 'Do I want to run for reelection or do I feel like I've accomplished the things I've liked to?' " DeBoy said. "Right now, I've achieved what I'd like to the in House of Delegates."
If DeBoy and Malone would have run for reelection in 2014, they would have faced a new set of constituents from Downtown Columbia.
The pair has represented District 12A, which covers parts of Elkridge, Ellicott City, Jessup and Baltimore County. But in 2014, their district will merge with District 12B, currently represented by Columbia Democrat Liz Bobo, creating a three-member district that stretches from Downtown Columbia to Halethrope.
Bobo indicated last year that she would retire in 2014 after 19 years in the state legislature.
DeBoy said redistricting "certainly" played a role in his decision.
"The two worlds of what I presently have as my base [in Baltimore County] and what's out in Columbia are obviously going to be polar opposites," he said.
DeBoy said he has been honored to serve for the past 10 years, and that he plans to finish strong throughout the remaining duration of his current term.
"I still have a year and a half left in this term," DeBoy said. "We've still got a lot to do. I'm not dropping off the face of the earth."
Though he will leave the House of Delegates, DeBoy did leave open the possibility that he will consider other political options.
"I'm just keeping my eyes and ears open to whatever might open up later on," DeBoy said. "I'm not done in political office by any stretch of the imagination," he said.
Malone currently serves as the chair of the Motor Vehicles and Transportation Subcommittee. DeBoy has been a member of the Appropriations Committee throughout the duration of his service. He is currently vice chairman of the Baltimore County delegation.
"I look forward to continuing to serve the rest of my term and promise to always be a positive influence in our community," Malone said.
The 2014 primary election is scheduled for June 2014. Candidates have until April 9, 2014 to file their candidacy.
Howard County Times reporter Blair Ames contributed to this story.