He announced a 500 million dollar package of executive actions and legislative proposals aimed at reducing the huge toll of American gun deaths.
The package includes a call on Congress to ban military-style assault weapons and high-capacity gun magazines, and it would close loopholes in the background check system for gun sales. Mr Obama also signed 23 executive actions - which require no congressional approval - including several aimed at improving access to data for background checks.
"This is the land of the free and the home of the brave and always will be," he said, acknowledging the constitutional right to bear arms. "But we've also long realised ... that with rights come responsibilities."
Families of the victims of last month's shooting were invited to the White House for the president's announcement, which promises to set up a bitter fight with a powerful pro-gun lobby that has long warned supporters that Mr Obama wanted to take away their guns.
The US has the highest rate of gun ownership in the world, and pro-gun groups see any move on gun restrictions as an offence against the right guaranteed by the Second Amendment of the US Constitution. Critics counter that the country's founding fathers never could have foreseen assault weapons more than two centuries ago, when guns were intended for the common, not individual, defence, guns were often stored in community areas and rifles fired one shot at a time.
The public appears receptive to stronger federal action on guns, with majorities of Americans favouring a nationwide ban on military-style rapid-fire weapons, according to a new Associated Press-GfK poll. The poll also shows 84% of adults would like to see the establishment of a federal standard for background checks for people buying guns at gun shows.
White House officials signalled that Mr Obama would seek to rally public support for the measures he puts forward. Seeking to avoid setting the president up for failure, they have emphasised that no single measure - even an assault weapons ban - would solve the scourge of gun violence. But without such a ban, or other sweeping Congress-approved measures, it is unclear whether executive actions alone can make any noticeable difference.
The president called for banning assault weapons and limiting ammunition magazines to 10 rounds or fewer, and he proposed a federal statute to stop purchases of guns by buyers who are acting for others. The president also called for a focus on universal background checks. Some 40% of gun sales take place without background checks, including those by private sellers at gun shows or over the internet.
The president's framework is based on recommendations from vice president Joe Biden, who led a wide-ranging task force on gun violence. Beyond the gun control measures, Mr Biden also made suggestions for improving mental health care and addressing violent images in video games, movies and television.