Chief Constable Iain Livingstone said planning for EU withdrawal was an "extremely dynamic and fast-moving" process.
He told a meeting of the Scottish Police Authority (SPA) board that an initial assessment had predicted delays for people and goods at airports and ports and said there were likely to be "mutual aid requests" from other forces.
He said he had spoken to the chief constable of the Police Service of Northern Ireland (PSNI) and pledged to offer his own officers, if needed.
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Mr Livingstone: "Planning is ongoing right across UK policing in relation to mitigating some of the impacts which may be required to manage potential consequences of Brexit.
"I have raised a number of concerns at this forum and in private with you...In recent days, hours there has been increased activity and focus as we move closer to March 29.
"From a policing perspective as with aspects of the Brexit debate, we are engaged in a extremely dynamic, fast-moving process, where, in truth, there are still many unknowns in existence.
"However it is my duty as chief constable to properly evaluate all confirmed and unconfirmed information available to prepare policing in Scotland for a wide range of scenarios and potential disruptions..."
Mr Livingstone has previously warned that his officers are preparing for potential food shortages following Brexit.
He told the SPA board that an initial impact assessment for Scotland had now been completed.
He added: "The type of planning is around a number of scenarios including potential delays around Scottish sea and airports for both people and goods and wider challenges across the UK leading to mutual aid requests.
"In this regard, at the end of last week I spoke at some length with the chief constable of the Police Service of Northern Ireland. We agreed that we would work together as best we can to provide support to our respective services. We are planning for an eventuality that should the chief constable of Northern Ireland need support from wider UK policing, he will feel one of the first places he may ask for support is from Police Scotland.
Published in The Scotsman