Mark Lotsu, Head of Biology at St John's School in Leatherhead, admitted he gave "improper assistance" to A and AS Level students in March 2015.
When the boarding school investigated, he also persuaded pupils to lie about the help they received.
Lotsu claimed he was under pressure to achieve better results, the BBC reported.
However, a written decision by the National College for Teaching and Leadership said such pressure "was normal across the education sector [and] in no way a justification for his actions".
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Lotsu helped pupils to cheat in their biology Investigative Skills Assignment in March 2015.
He provided them with some answers and revision sheets and allowed those who scored badly to rewrite work on to photocopied pages which were then stapled to their original papers.
The ruling stated: "The panel was satisfied that Mr Lotsu's conduct in dishonestly interfering with national examinations and asking pupils to lie on his behalf was misconduct of a serious nature, falling significantly short of the standard of behavior expected of a teacher."
The panel recommended the ban from teaching is reviewed in two years, but Jayne Millions, from the Department for Education, struck him off "indefinitely" and this cannot be reviewed for three years.