Mr Trump said he thought the UK and US could end up with a "real trade deal" without tariffs and called Sir Keir a "tough negotiator" who had tried to persuade him not to impose trade tariffs on the UK.
Mr Starmer followed Mr Macron into the Oval Office in an effort to win over Mr Trump after his administration held unilateral talks with Russia last week, without Ukraine, in a move that set off sirens throughout Europe's capitals.
During the meeting and a subsequent news conference, the two world leaders exchanged warm words - Mr Trump described Sir Keir as a "special man" and a "great gentleman", while the British PM praised the US leader for "changing the conversation" on Ukraine.
While Mr Trump said "if it [a peace deal] doesn't happen quickly, it may not happen at all", Sir Keir said "history must be on the side of the peacemaker, not the invader.".
On the Chagos Islands deal, over which some have criticised Mr Starmer, Mr Trump said the plan to give up sovereignty and lease back the US-UK base would "work out well".