Season 1, where Ben, Gwen, and Kevin travel all over the universe to try and stop Lord Gemini and the League of Zodiacs.
Welcome to Osmos V
Airdate: September 9, 2011, Number: 1, Number Overall: 151
Aggregor escaped from the Null Void and heads to Osmos V to destroy it.
Triple Trouble
Airdate: September 16, 2011, Number: 2, Number Overall: 152
Lord Gemini hires Albedo to capture the Maximatrix, but loses to Ben after accidently pulling Ben 10,000 back in time.
The League of Zodiacs
Airdate: September 23, 2011, Number: 3, Number Overall: 153
The League of Zodiacs comes to Earth and takes the Maximatrix from Ben. Ben then puts the Ultimatrix back on.
Freezer Burn
Airdate: September 30, 2011, Number: 4, Number Overall: 154
Ben heads to the planet of Stomlon to stop a war between the colonists of the planet.
The Ancient Horn
Airdate: October 7, 2011, Number: 5, Number Overall: 155
Ben discovers an alien species with a horn that can destroy Codon, and thus nullify his powers.
Call of the Wild
Airdate: October 14, 2011, Number: 6, Number Overall: 156
Vilgax is temporarily moved to Area 51 when Azmuth decides to upgrade the Null Void's defenses.
The Star Map Cometh
Airdate: October 21, 2011, Number: 7, Number Overall: 157
Lord Gemini steals the ancient horn and uses it to open the Great Gates and collect the Star Map.
Don't Look Into the Light
Airdate: October 28, 2011, Number: 8, Number Overall: 158
Lord Gemini send Sir Ophiuchus on a quest after Sir Cancer questions his methods. During his quest, he accidently releases the Flashers.
Off the Grid
Airdate: November 5, 2011, Number: 9, Number Overall: 159
When Kevin leaves to visit his father's grave, Ben and Gwen must work alone to stop Vulkanus from destroying the Earth.
Into the Antarctic
Airdate: November 12, 2011, Number: 10, Number Overall: 160
The League of Zodiacs begins their search for the DNA Code
The DNA Code
Airdate: November 19, 2011, Number: 11, Number Overall: 161
After successfully finding the DNA Code, Lord Gemini declares the war of Matrix Prime to be over.
X Marks the Spot
And Then There Were None
War of the Thirteen
Let the Games Begin
The First Zodiac
Paradox in the Second Universe
Down to Earth
The Inner Circle
Mission: Impossible
The Last Stand of the Zodiac League Part 1
The Last Stand of the Zodiac League Part 2