Ismael Watson, 27, travelled to Turkey and attempted to cross into Syria but was stopped and sent back to Britain after being caught by undercover officers.
He denied preparation of terrorist acts but refused to attend his trial or be represented by a defence lawyer.
His first trial at the Old Bailey was abandoned and following a two-day retrial Watson, who chose to remain in his prison cell, was found guilty in his absence.
Judge Anuja Dhir QC set a sentencing hearing for October 4 and gave him the option of having a pre-sentence report.
She said: "I want to give him the opportunity to attend on that date. If he does not come on that date I have asked if he would like a pre-sentence report and there is no reason why the day after or some day that week we cannot proceed to sentence."
The court had heard how the defendant, formally known as Jack Watson, came from a non-Muslim family in Liverpool and was described by his mother as "meek, mild and easily influenced".
Following his conversion to Islam, he was "quickly radicalised" and in 2015, he married Sharmina Begum at a mosque in Birmingham.
The couple moved into a shared house in Walsall but the relationship broke down by January last year as Watson's views became increasingly extreme after watching IS videos, jurors heard.
Prosecutor Oliver Glasgow QC had told jurors Watson made preparations to join IS between January last year and February 23 this year.
He took a flight to Morocco then made his way to Turkey and allegedly sought help to cross the border into Syria through contacts on the internet, not realising he was speaking to two undercover security service agents.
In a conversation on March 30 last year, an officer asked him if he had been "hot" before he left Britain, and Watson replied: "Yes I was hot. My wife snitched on me and left. While pregnant told them everything..."
On what jobs he wanted to do in Syria, Watson suggested he could help with film-making, proof-reading and cooking.
In encrypted Telegram chats with another officer, he described how he slicked back his hair to look more Syrian but admitted he "can only change face so much".
Watson was detained in Turkey and sent back to Britain in February.
Jurors had been told he was not in court but were warned not to hold it against him. Watson offered no defence and was convicted by a jury after 20 minutes of deliberations.