The study determined the effects of laboratory learning environment on students’ learning outcomes in secondary school Chemistry. The study adopted the pre-test - post-test, quasi - experimental control group design. The sample comprised 293 Senior Secondary III Chemistry students in their intact classes from six schools purposively selected from six Local Government Areas (LGAs) of Ondo State. Two research instruments were used for collection of data, namely: Chemistry Practical Achievement Test (CPAT) and Chemistry Attitude Scale (CAS). Data collected were analysed using Analysis of Covariance (ANCOVA). Results showed that integration dimension of Chemistry laboratory learning environment has the most significant effect on the learners’ performance, closely followed by Student Cohesiveness and Open-Endedness. Results also indicated that student cohesiveness dimension of laboratory learning environment has the most significant effect on the learners’ attitude, closely followed by Rule clarity. It is recommended among others that the five dimensions of the laboratory learning environment should be used to determine the actual situation of the Chemistry laboratory learning environment. This would enable the Chemistry teachers know the particular environment variable(s) that would enhance the teaching and learning of the subject.