Condensed Consolidated Statements of Operations and Comprehensive Income/(Loss) (Unaudited) - USD ($)
 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Income Statement [Abstract]    
Revenues $ 43,130,934 $ 43,518,384
Cost of revenues 26,162,582 25,897,181
Gross profit 16,968,352 17,621,203
Operating expenses    
General and administrative 22,538,496 20,363,728
Research and development 3,171,676 1,827,286
Total operating expenses 25,710,172 22,191,014
Operating income/(loss) (8,741,820) (4,569,811)
Other income/(expense)    
Other income/(expense) 8,758,212 1,821,029
Settlement Agreement - Related Party 3,674,165
Interest Expense (2,921,345) (4,607,453)
Total other income/(expense), net 9,511,032 (2,786,424)
Net loss before income taxes 769,212 (7,356,235)
Income tax benefit/(expense) (375,434) (2,073,835)
Income/Loss from Continuing operations 393,778 (9,430,070)
Loss from discontinued operations, net of tax (8,280,047) (812,895)
Net income/(loss) (7,886,269) (10,242,965)
Less income/(loss) in noncontrolling interest (78,274) 227,116
Net income/(loss) attributable to Cemtrex, Inc. shareholders (7,807,995) (10,470,081)
Net income/(loss) (7,886,269) (10,242,965)
Other comprehensive income/(loss)    
Foreign currency translation gain/(loss) 996,100 57,639
Defined benefit plan actuarial gain/(loss) 87,895
Comprehensive income/(loss) (6,802,274) (10,185,326)
Less comprehensive income/(loss) attributable to noncontrolling interest 78,274 (227,116)
Comprehensive income/(loss) attributable to Cemtrex, Inc. shareholders $ (6,880,548) $ (9,958,210)
Income/(loss) Per Share-Basic    
Income/(loss) Per Share-Basic- Continuing operations $ 0.02 $ (1.00)
Income/(loss) Per Share-Basic - Discontinued operations (0.44) (0.08)
Income/(loss) Per Share-Diluted- Continuing operations    
Income/(loss) Per Share-Diluted 0.02 (1.00)
Income/(loss) Per Share-Diluted - Discontinued operations $ (0.44) $ (0.08)
Weighted Average Number of Shares-Basic 18,911,746 9,611,516
Weighted Average Number of Shares-Diluted 18,911,746 9,611,516