Bilal Shafayat's second Championship century of the season put Notts in a strong position at 259-2, only 80 behind Sussex after two days at Hove.
After adding only 47 for the loss of their final five wickets, Sussex were wicketless between lunch and tea.
Will Jefferson hit eight fours and two sixes in his 80, while Shafayat fired 16 fours and reached his hundred with a six off leg-spinner Will Beer.
Mark Wagh was dropped by Ollie Rayner on 16 and reached 31 at the close.
Paceman Charlie Shreck produced a burst of four wickets for eight runs in 27 balls as Sussex were dismissed in 91 minutes on the second morning.
Notts made a rapid start which was only halted but Jefferson should have been dismissed when just seven, dropped at slip off Jason Lewry.
He launched Ollie Rayner for two sixes and reached fifty from 78 balls, but after making his highest score of the season he was caught down the leg-side off spinner Rayner.
Shafayat was bowled attempting to work left-arm swing bowler Lewry off his legs, but Rayner's miss running back from mid-off allowed Wagh a reprieve and Notts the advantage.
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