The night began around 10:15 p.m. with at STK restaurant in Los Angeles.
Odom, 29, arrived with Girls Gone Wild founder Joe Francis, Khloe's brother Robert and Scott Disick, the father of Kourtney Kardashian's baby, as well as some Los Angeles Lakers teammates and high school pals.
Odom — who had canceled a wilder bash slated at hot spot Les Deux — bought a round of Johnny Walker & Lemon Drop shots for his guests. (Disick, 26, stuck to champagne.)
One of his pals then gave a toast, "This is to one wedding ring and many championship rings!"
Odom yelled, "Mazel Tov!" and the crowd laughed.
They all dined on steaks, macaroni and cheese, fingerling potatoes, Yukon mashed potatoes and tuna tartare.
Disick spent a lot of time smoking alone on the patio, rarely interacting with Odom and his pals.
But "Lamar was giddy, really happy to be around his friends, hugging a lot of them," a source tells Usmagazine.com. "Lamar even took a timeout to take photos with diners."
Around 11:30 p.m., the crowed then headed to West Hollywood club Guys and Dolls, where they were escorted to their table in the middle of the club.
They all sipped on champagne.
"Lamar was in a great mood," a clubgoer tells Us. "I've never seen him smiling and laughing so much. He was the center of attention all night, and he was loving it!"
At 1:28 a.m. the music stopped, Odom's teammate Ron Artest grabbed the microphone and announced, "Everyone raise their glass ... Sunday is the big day. Big baller's getting married!"
Clubgoers went crazy, screaming, whistling, and clapping.
"Lamar was grinning from ear to ear," says the witness.
The DJ followed the toast up with the 50 Cent track, "I Run New York." (Odom is a native of Queens, N.Y.)
Says the clubgoer, "The drinking, dancing, and celebrating carried on until close. They left at close."
Where was Khloe, 25?
At the Viceroy Santa Monica, lounging poolside with her family and friends.
The bride-to-be spent most of the night texting while they enjoyed a mellow dinner at the luxury hotel's restaurant Whist.