The London-born 23-year-old - nicknamed Tomahawk - will join up with Warriors after completing his studying modern languages at Oxford University.
Tight-head prop Tomaszczyk was previously part of the England Under-18 set-up alongside Tom Wood and Matt Mullan and has also played for Argentinean Division One side Lomas Athletic in 2006
"We're pleased to announce that we've signed tight-head prop Oliver Tomaszczyk. He attracted a lot of interest from other clubs including Munster and so we are delighted that he has chosen the Warriors," said Head Coach Richard Hill.
"Oliver comes to us with a very good pedigree. Over the last few years he's dedicated himself to his studies at Oxford University, culminating in his appearance in the Varsity match in which he was outstanding.
"I know the Oxford University Coach Steve Hill very well as we coached the England Students together and he has excellent judgment."
"I have also been impressed that he has gone off to play in Argentina as part of his personal and academic development. I'm sure that experience of scrummaging in Argentina will help him develop even more quickly."
When commenting on his move to Sixways, Tomaszczyk stated "I am thoroughly looking forward to the challenge ahead, Warriors have traditionally had an intense and physical pack and I plan to contribute towards developing this further."
Tomaszczyk added "the competition at Sixways is impressive and I hope the competition for places will bring out the best in all of us"