The Milwaukee Brewers star accepted the 65-game penalty, 15 games more than the one he avoided last year when an arbitrator overturned his positive test for elevated testosterone because the urine sample had been improperly handled.
"I am not perfect. I realize now that I have made some mistakes. I am willing to accept the consequences of those actions," he said in a statement.
Braun, injured Yankees star Alex Rodriguez and more than a dozen players were targeted by MLB following a report by Miami New Times in January that they had been connected with Biogenesis of America, a now-closed anti-aging clinic.
MLB Commissioner Bud Selig announced the penalty Monday, citing Braun for multiple unspecified "violations" of baseball's drug program and labor contract. Braun will miss the Milwaukee Brewers' final 65 games without pay, costing him about $3 million of his $8.5 million salary.
Under the agreement reached by MLB and the players' association the specifics of Braun's admission won't be made public. The sides also wouldn't say whether this counted as a single violation or more under baseball's drug agreement.
"We commend Ryan Braun for taking responsibility for his past actions," said Rob Manfred, MLB's executive vice president for economics and league affairs. "We all agree that it is in the best interests of the game to resolve this matter. When Ryan returns, we look forward to him making positive contributions to Major League Baseball, both on and off the field."
Union head Michael Weiner said in a statement: "I am deeply gratified to see Ryan taking this bold step. It vindicates the rights of all players under the joint drug program. It is good for the game that Ryan will return soon to continue his great work both on and off the field."
Braun's acceptance of a suspension marks a 180-degree turnaround from his defiant spring training news conference in Phoenix last year, after his 50-game ban was overturned.
"We won," he said then, "because the truth is on my side. The truth is always relevant, and at the end of the day, the truth prevailed."
Braun became the latest star tripped up by baseball's drug rules.
The sport was criticized for allowing bulked up sluggers to set power records in the 1990s and only started testing in 2003. Since then, testing and penalties have become more stringent and last year San Francisco's Melky Cabrera was suspended for 50 games, just weeks after he was voted MVP of the All-Star game.
Four All-Stars this year have been linked in media reports to Biogenesis: Texas outfielder Nelson Cruz, San Diego shortstop Everth Cabrera, Oakland pitcher Bartolo Colon and Detroit shortstop Jhonny Peralta.
Other players reportedly tied to Biogenesis include Cabrera, now with the Toronto Blue Jays, Yankees catcher Francisco Cervelli and Seattle catcher Jesus Montero.
Weiner said last week that arbitration hearings for players contesting suspensions likely would not start until September, which would delay any penalty until next season. But he also indicated the union would urge players to make a deal and get a suspension over with if there was strong evidence of guilt.