The measures would restrict the fundamental right to strike and impose many other excessive and unnecessary burdens on unions.
Monday’s rally, with a range of guest speakers, begins at 1pm, at Methodist Central Hall, Storey's Gate, London SW1H 9NH.
Those who have secured an appointment to lobby their MP will move across the road to the House of Commons from 2.30pm onwards.
All Prospect members are encouraged to attend the rally, whether you are meeting your MP or not.
Prospect parliamentary and campaigns officer Graham Stewart said: “If you work in London and can spare your lunch hour to attend, it would be very much appreciated.
“Just as important is that individual members keep up the pressure on politicians by writing to their own MP expressing their concern over the contents of the bill.”