The Bill, which the union movement said delivers on a clear manifesto commitment, has faced repeated opposition in the Lords despite months of debate and scrutiny.
TUC General Secretary Paul Nowak said: “Years of Tory cuts and underinvestment have left big challenges in the jobs market – including continued growth in the use of insecure zero hours contracts."
The union body has urged the Government to “stand firm” in the face of attacks on the Employment Rights Bill.
In recent days, both Conservative and Reform parties characterised Government plans to protect workers from third-party harassment as "an end to pub banter."