More than 1,100 members of the Community union claimed there had been a lack of consultation when SSI's Redcar plant closed.
The payout could have been more than £14m but SSI's liquidation means workers will only get the government's contribution.
Union general secretary Roy Rickhuss said it was a "deserved victory".
"However, as we have said before, this small victory will not compensate for the devastation from the end of steel making," he said.
Workers will receive a share of the award from the government's redundancy payments office up to a maximum of 8 weeks' pay, subject to statutory limits and deductions.
Other workers were waiting for the outcome of a case being made by the Unite union, Community said.
SSI blamed a global slump in the value of steel for its original decision to pause production at the Redcar works.
The Teesside furnaces and coke ovens were closed with a loss of 2,200 jobs in October.
Former staff at a closed steelworks have been awarded £6.25m by an employment judge, their union has said.