"I understand the severity of my actions and take full responsibility," Phelps tweeted and said in a prepared statement released through his agent. "I know these words may not mean much right now but I am deeply sorry to everyone I have let down."
Phelps, 29, was going 84 mph in a 45 mph zone and was also seen crossing double lane lines, police said.
The officers realized he was intoxicated and gave him a field sobriety test, authorities said.
"Mr. Phelps was identified as the driver by his driver’s license and appeared to be under the influence. He was unable to perform satisfactorily a series of standard field sobriety tests," a spokesperson for Maryland Transportation Authority told ABC.
Phelps has been charged with speeding, DUI and crossing double lane lines, police said. He has since been released, they added.
This is the athlete's second DUI arrest. He was arrested in 2004, also in his native Maryland. He pleaded guilty to that arrest and got 18 months probation.
Phelps is one of the most notable Olympians ever, winning 22 total medals -- 18 of which are gold. He won his first Olympic gold in Athens in 2004 and competed recently in the 2012 London Games.